1PARALLEL_ALTERNATIVES(7) parallel PARALLEL_ALTERNATIVES(7)
2
6 parallel_alternatives - Alternatives to GNU parallel
7
9 There are a lot programs with some of the functionality of GNU
10 parallel. GNU parallel strives to include the best of the functionality
11 without sacrificing ease of use.
12 parallel has existed since 2002 and as GNU parallel since 2010. A lot
14 of the alternatives have not had the vitality to survive that long, but
15 have come and gone during that time.
16 GNU parallel is actively maintained with a new release every month
18 since 2010. Most other alternatives are fleeting interests of the
19 developers with irregular releases and only maintained for a few years.
20 SUMMARY TABLE
22 The following features are in some of the comparable tools:
23 Inputs
25 I1. Arguments can be read from stdin
26 I2. Arguments can be read from a file
27 I3. Arguments can be read from multiple files
28 I4. Arguments can be read from command line
29 I5. Arguments can be read from a table
30 I6. Arguments can be read from the same file using #! (shebang)
31 I7. Line oriented input as default (Quoting of special chars not
32 needed)
33 Manipulation of input
35 M1. Composed command
36 M2. Multiple arguments can fill up an execution line
37 M3. Arguments can be put anywhere in the execution line
38 M4. Multiple arguments can be put anywhere in the execution line
39 M5. Arguments can be replaced with context
40 M6. Input can be treated as the complete command line
41 Outputs
43 O1. Grouping output so output from different jobs do not mix
44 O2. Send stderr (standard error) to stderr (standard error)
45 O3. Send stdout (standard output) to stdout (standard output)
46 O4. Order of output can be same as order of input
47 O5. Stdout only contains stdout (standard output) from the command
48 O6. Stderr only contains stderr (standard error) from the command
49 O7. Buffering on disk
50 O8. Cleanup of file if killed
51 O9. Test if disk runs full during run
52 O10. Output of a line bigger than 4 GB
53 Execution
55 E1. Running jobs in parallel
56 E2. List running jobs
57 E3. Finish running jobs, but do not start new jobs
58 E4. Number of running jobs can depend on number of cpus
59 E5. Finish running jobs, but do not start new jobs after first failure
60 E6. Number of running jobs can be adjusted while running
61 E7. Only spawn new jobs if load is less than a limit
62 Remote execution
64 R1. Jobs can be run on remote computers
65 R2. Basefiles can be transferred
66 R3. Argument files can be transferred
67 R4. Result files can be transferred
68 R5. Cleanup of transferred files
69 R6. No config files needed
70 R7. Do not run more than SSHD's MaxStartups can handle
71 R8. Configurable SSH command
72 R9. Retry if connection breaks occasionally
73 Semaphore
75 S1. Possibility to work as a mutex
76 S2. Possibility to work as a counting semaphore
77 Legend
79 - = no
80 x = not applicable
81 ID = yes
82 As every new version of the programs are not tested the table may be
84 outdated. Please file a bug-report if you find errors (See REPORTING
85 BUGS).
86 parallel: I1 I2 I3 I4 I5 I6 I7 M1 M2 M3 M4 M5 M6 O1 O2 O3 O4 O5 O6 O7
88 O8 O9 O10 E1 E2 E3 E4 E5 E6 E7 R1 R2 R3 R4 R5 R6 R7 R8 R9 S1 S2
89 find -exec: - - - x - x - - M2 M3 - - - - - O2 O3 O4 O5 O6 -
91 - - - - - - - - - - - - - - - x x
92 make -j: - - - - - - - - - - - - - O1 O2 O3 - x O6 E1 - -
94 - E5 - - - - - - - - - - - -
95 DIFFERENCES BETWEEN xargs AND GNU Parallel
97 Summary table (see legend above): I1 I2 - - - - - - M2 M3 - - - - O2 O3
98 - O5 O6 E1 - - - - - - - - - - - x - - - - -
99 xargs offers some of the same possibilities as GNU parallel.
101 xargs deals badly with special characters (such as space, \, ' and ").
103 To see the problem try this:
104 touch important_file
106 touch 'not important_file'
107 ls not* | xargs rm
108 mkdir -p "My brother's 12\" records"
109 ls | xargs rmdir
110 touch 'c:\windows\system32\clfs.sys'
111 echo 'c:\windows\system32\clfs.sys' | xargs ls -l
112 You can specify -0, but many input generators are not optimized for
114 using NUL as separator but are optimized for newline as separator. E.g.
115 awk, ls, echo, tar -v, head (requires using -z), tail (requires using
116 -z), sed (requires using -z), perl (-0 and \0 instead of \n), locate
117 (requires using -0), find (requires using -print0), grep (requires
118 using -z or -Z), sort (requires using -z).
119 GNU parallel's newline separation can be emulated with:
121 cat | xargs -d "\n" -n1 command
123 xargs can run a given number of jobs in parallel, but has no support
125 for running number-of-cpu-cores jobs in parallel.
126 xargs has no support for grouping the output, therefore output may run
128 together, e.g. the first half of a line is from one process and the
129 last half of the line is from another process. The example Parallel
130 grep cannot be done reliably with xargs because of this. To see this in
131 action try:
132 parallel perl -e '\$a=\"1\".\"{}\"x10000000\;print\ \$a,\"\\n\"' \
134 '>' {} ::: a b c d e f g h
135 # Serial = no mixing = the wanted result
136 # 'tr -s a-z' squeezes repeating letters into a single letter
137 echo a b c d e f g h | xargs -P1 -n1 grep 1 | tr -s a-z
138 # Compare to 8 jobs in parallel
139 parallel -kP8 -n1 grep 1 ::: a b c d e f g h | tr -s a-z
140 echo a b c d e f g h | xargs -P8 -n1 grep 1 | tr -s a-z
141 echo a b c d e f g h | xargs -P8 -n1 grep --line-buffered 1 | \
142 tr -s a-z
143 Or try this:
145 slow_seq() {
147 echo Count to "$@"
148 seq "$@" |
149 perl -ne '$|=1; for(split//){ print; select($a,$a,$a,0.100);}'
150 }
151 export -f slow_seq
152 # Serial = no mixing = the wanted result
153 seq 8 | xargs -n1 -P1 -I {} bash -c 'slow_seq {}'
154 # Compare to 8 jobs in parallel
155 seq 8 | parallel -P8 slow_seq {}
156 seq 8 | xargs -n1 -P8 -I {} bash -c 'slow_seq {}'
157 xargs has no support for keeping the order of the output, therefore if
159 running jobs in parallel using xargs the output of the second job
160 cannot be postponed till the first job is done.
161 xargs has no support for running jobs on remote computers.
163 xargs has no support for context replace, so you will have to create
165 the arguments.
166 If you use a replace string in xargs (-I) you can not force xargs to
168 use more than one argument.
169 Quoting in xargs works like -q in GNU parallel. This means composed
171 commands and redirection require using bash -c.
172 ls | parallel "wc {} >{}.wc"
174 ls | parallel "echo {}; ls {}|wc"
175 becomes (assuming you have 8 cores and that none of the filenames
177 contain space, " or ').
178 ls | xargs -d "\n" -P8 -I {} bash -c "wc {} >{}.wc"
180 ls | xargs -d "\n" -P8 -I {} bash -c "echo {}; ls {}|wc"
181 https://www.gnu.org/software/findutils/
183 DIFFERENCES BETWEEN find -exec AND GNU Parallel
185 find -exec offers some of the same possibilities as GNU parallel.
186 find -exec only works on files. Processing other input (such as hosts
188 or URLs) will require creating these inputs as files. find -exec has no
189 support for running commands in parallel.
190 https://www.gnu.org/software/findutils/ (Last checked: 2019-01)
192 DIFFERENCES BETWEEN make -j AND GNU Parallel
194 make -j can run jobs in parallel, but requires a crafted Makefile to do
195 this. That results in extra quoting to get filenames containing
196 newlines to work correctly.
197 make -j computes a dependency graph before running jobs. Jobs run by
199 GNU parallel does not depend on each other.
200 (Very early versions of GNU parallel were coincidentally implemented
202 using make -j).
203 https://www.gnu.org/software/make/ (Last checked: 2019-01)
205 DIFFERENCES BETWEEN ppss AND GNU Parallel
207 Summary table (see legend above): I1 I2 - - - - I7 M1 - M3 - - M6 O1 -
208 - x - - E1 E2 ?E3 E4 - - - R1 R2 R3 R4 - - ?R7 ? ? - -
209 ppss is also a tool for running jobs in parallel.
211 The output of ppss is status information and thus not useful for using
213 as input for another command. The output from the jobs are put into
214 files.
215 The argument replace string ($ITEM) cannot be changed. Arguments must
217 be quoted - thus arguments containing special characters (space '"&!*)
218 may cause problems. More than one argument is not supported. Filenames
219 containing newlines are not processed correctly. When reading input
220 from a file null cannot be used as a terminator. ppss needs to read the
221 whole input file before starting any jobs.
222 Output and status information is stored in ppss_dir and thus requires
224 cleanup when completed. If the dir is not removed before running ppss
225 again it may cause nothing to happen as ppss thinks the task is already
226 done. GNU parallel will normally not need cleaning up if running
227 locally and will only need cleaning up if stopped abnormally and
228 running remote (--cleanup may not complete if stopped abnormally). The
229 example Parallel grep would require extra postprocessing if written
230 using ppss.
231 For remote systems PPSS requires 3 steps: config, deploy, and start.
233 GNU parallel only requires one step.
234 EXAMPLES FROM ppss MANUAL
236 Here are the examples from ppss's manual page with the equivalent using
238 GNU parallel:
239 1$ ./ppss.sh standalone -d /path/to/files -c 'gzip '
241 1$ find /path/to/files -type f | parallel gzip
243 2$ ./ppss.sh standalone -d /path/to/files -c 'cp "$ITEM" /destination/dir '
245 2$ find /path/to/files -type f | parallel cp {} /destination/dir
247 3$ ./ppss.sh standalone -f list-of-urls.txt -c 'wget -q '
249 3$ parallel -a list-of-urls.txt wget -q
251 4$ ./ppss.sh standalone -f list-of-urls.txt -c 'wget -q "$ITEM"'
253 4$ parallel -a list-of-urls.txt wget -q {}
255 5$ ./ppss config -C config.cfg -c 'encode.sh ' -d /source/dir \
257 -m 192.168.1.100 -u ppss -k ppss-key.key -S ./encode.sh \
258 -n nodes.txt -o /some/output/dir --upload --download;
259 ./ppss deploy -C config.cfg
260 ./ppss start -C config
261 5$ # parallel does not use configs. If you want a different username put it in nodes.txt: user@hostname
263 find source/dir -type f |
264 parallel --sshloginfile nodes.txt --trc {.}.mp3 lame -a {} -o {.}.mp3 --preset standard --quiet
265 6$ ./ppss stop -C config.cfg
267 6$ killall -TERM parallel
269 7$ ./ppss pause -C config.cfg
271 7$ Press: CTRL-Z or killall -SIGTSTP parallel
273 8$ ./ppss continue -C config.cfg
275 8$ Enter: fg or killall -SIGCONT parallel
277 9$ ./ppss.sh status -C config.cfg
279 9$ killall -SIGUSR2 parallel
281 https://github.com/louwrentius/PPSS
283 DIFFERENCES BETWEEN pexec AND GNU Parallel
285 Summary table (see legend above): I1 I2 - I4 I5 - - M1 - M3 - - M6 O1
286 O2 O3 - O5 O6 E1 - - E4 - E6 - R1 - - - - R6 - - - S1 -
287 pexec is also a tool for running jobs in parallel.
289 EXAMPLES FROM pexec MANUAL
291 Here are the examples from pexec's info page with the equivalent using
293 GNU parallel:
294 1$ pexec -o sqrt-%s.dat -p "$(seq 10)" -e NUM -n 4 -c -- \
296 'echo "scale=10000;sqrt($NUM)" | bc'
297 1$ seq 10 | parallel -j4 'echo "scale=10000;sqrt({})" | \
299 bc > sqrt-{}.dat'
300 2$ pexec -p "$(ls myfiles*.ext)" -i %s -o %s.sort -- sort
302 2$ ls myfiles*.ext | parallel sort {} ">{}.sort"
304 3$ pexec -f image.list -n auto -e B -u star.log -c -- \
306 'fistar $B.fits -f 100 -F id,x,y,flux -o $B.star'
307 3$ parallel -a image.list \
309 'fistar {}.fits -f 100 -F id,x,y,flux -o {}.star' 2>star.log
310 4$ pexec -r *.png -e IMG -c -o - -- \
312 'convert $IMG ${IMG%.png}.jpeg ; "echo $IMG: done"'
313 4$ ls *.png | parallel 'convert {} {.}.jpeg; echo {}: done'
315 5$ pexec -r *.png -i %s -o %s.jpg -c 'pngtopnm | pnmtojpeg'
317 5$ ls *.png | parallel 'pngtopnm < {} | pnmtojpeg > {}.jpg'
319 6$ for p in *.png ; do echo ${p%.png} ; done | \
321 pexec -f - -i %s.png -o %s.jpg -c 'pngtopnm | pnmtojpeg'
322 6$ ls *.png | parallel 'pngtopnm < {} | pnmtojpeg > {.}.jpg'
324 7$ LIST=$(for p in *.png ; do echo ${p%.png} ; done)
326 pexec -r $LIST -i %s.png -o %s.jpg -c 'pngtopnm | pnmtojpeg'
327 7$ ls *.png | parallel 'pngtopnm < {} | pnmtojpeg > {.}.jpg'
329 8$ pexec -n 8 -r *.jpg -y unix -e IMG -c \
331 'pexec -j -m blockread -d $IMG | \
332 jpegtopnm | pnmscale 0.5 | pnmtojpeg | \
333 pexec -j -m blockwrite -s th_$IMG'
334 8$ # Combining GNU B<parallel> and GNU B<sem>.
336 ls *jpg | parallel -j8 'sem --id blockread cat {} | jpegtopnm |' \
337 'pnmscale 0.5 | pnmtojpeg | sem --id blockwrite cat > th_{}'
338 # If reading and writing is done to the same disk, this may be
340 # faster as only one process will be either reading or writing:
341 ls *jpg | parallel -j8 'sem --id diskio cat {} | jpegtopnm |' \
342 'pnmscale 0.5 | pnmtojpeg | sem --id diskio cat > th_{}'
343 https://www.gnu.org/software/pexec/
345 DIFFERENCES BETWEEN xjobs AND GNU Parallel
347 xjobs is also a tool for running jobs in parallel. It only supports
348 running jobs on your local computer.
349 xjobs deals badly with special characters just like xargs. See the
351 section DIFFERENCES BETWEEN xargs AND GNU Parallel.
352 EXAMPLES FROM xjobs MANUAL
354 Here are the examples from xjobs's man page with the equivalent using
356 GNU parallel:
357 1$ ls -1 *.zip | xjobs unzip
359 1$ ls *.zip | parallel unzip
361 2$ ls -1 *.zip | xjobs -n unzip
363 2$ ls *.zip | parallel unzip >/dev/null
365 3$ find . -name '*.bak' | xjobs gzip
367 3$ find . -name '*.bak' | parallel gzip
369 4$ ls -1 *.jar | sed 's/\(.*\)/\1 > \1.idx/' | xjobs jar tf
371 4$ ls *.jar | parallel jar tf {} '>' {}.idx
373 5$ xjobs -s script
375 5$ cat script | parallel
377 6$ mkfifo /var/run/my_named_pipe;
379 xjobs -s /var/run/my_named_pipe &
380 echo unzip 1.zip >> /var/run/my_named_pipe;
381 echo tar cf /backup/myhome.tar /home/me >> /var/run/my_named_pipe
382 6$ mkfifo /var/run/my_named_pipe;
384 cat /var/run/my_named_pipe | parallel &
385 echo unzip 1.zip >> /var/run/my_named_pipe;
386 echo tar cf /backup/myhome.tar /home/me >> /var/run/my_named_pipe
387 http://www.maier-komor.de/xjobs.html (Last checked: 2019-01)
389 DIFFERENCES BETWEEN prll AND GNU Parallel
391 prll is also a tool for running jobs in parallel. It does not support
392 running jobs on remote computers.
393 prll encourages using BASH aliases and BASH functions instead of
395 scripts. GNU parallel supports scripts directly, functions if they are
396 exported using export -f, and aliases if using env_parallel.
397 prll generates a lot of status information on stderr (standard error)
399 which makes it harder to use the stderr (standard error) output of the
400 job directly as input for another program.
401 EXAMPLES FROM prll's MANUAL
403 Here is the example from prll's man page with the equivalent using GNU
405 parallel:
406 1$ prll -s 'mogrify -flip $1' *.jpg
408 1$ parallel mogrify -flip ::: *.jpg
410 https://github.com/exzombie/prll (Last checked: 2019-01)
412 DIFFERENCES BETWEEN dxargs AND GNU Parallel
414 dxargs is also a tool for running jobs in parallel.
415 dxargs does not deal well with more simultaneous jobs than SSHD's
417 MaxStartups. dxargs is only built for remote run jobs, but does not
418 support transferring of files.
419 https://web.archive.org/web/20120518070250/http://www.
421 semicomplete.com/blog/geekery/distributed-xargs.html (Last checked:
422 2019-01)
423 DIFFERENCES BETWEEN mdm/middleman AND GNU Parallel
425 middleman(mdm) is also a tool for running jobs in parallel.
426 EXAMPLES FROM middleman's WEBSITE
428 Here are the shellscripts of
430 https://web.archive.org/web/20110728064735/http://mdm.
431 berlios.de/usage.html ported to GNU parallel:
432 1$ seq 19 | parallel buffon -o - | sort -n > result
434 cat files | parallel cmd
435 find dir -execdir sem cmd {} \;
436 https://github.com/cklin/mdm (Last checked: 2019-01)
438 DIFFERENCES BETWEEN xapply AND GNU Parallel
440 xapply can run jobs in parallel on the local computer.
441 EXAMPLES FROM xapply's MANUAL
443 Here are the examples from xapply's man page with the equivalent using
445 GNU parallel:
446 1$ xapply '(cd %1 && make all)' */
448 1$ parallel 'cd {} && make all' ::: */
450 2$ xapply -f 'diff %1 ../version5/%1' manifest | more
452 2$ parallel diff {} ../version5/{} < manifest | more
454 3$ xapply -p/dev/null -f 'diff %1 %2' manifest1 checklist1
456 3$ parallel --link diff {1} {2} :::: manifest1 checklist1
458 4$ xapply 'indent' *.c
460 4$ parallel indent ::: *.c
462 5$ find ~ksb/bin -type f ! -perm -111 -print | \
464 xapply -f -v 'chmod a+x' -
465 5$ find ~ksb/bin -type f ! -perm -111 -print | \
467 parallel -v chmod a+x
468 6$ find */ -... | fmt 960 1024 | xapply -f -i /dev/tty 'vi' -
470 6$ sh <(find */ -... | parallel -s 1024 echo vi)
472 6$ find */ -... | parallel -s 1024 -Xuj1 vi
474 7$ find ... | xapply -f -5 -i /dev/tty 'vi' - - - - -
476 7$ sh <(find ... | parallel -n5 echo vi)
478 7$ find ... | parallel -n5 -uj1 vi
480 8$ xapply -fn "" /etc/passwd
482 8$ parallel -k echo < /etc/passwd
484 9$ tr ':' '\012' < /etc/passwd | \
486 xapply -7 -nf 'chown %1 %6' - - - - - - -
487 9$ tr ':' '\012' < /etc/passwd | parallel -N7 chown {1} {6}
489 10$ xapply '[ -d %1/RCS ] || echo %1' */
491 10$ parallel '[ -d {}/RCS ] || echo {}' ::: */
493 11$ xapply -f '[ -f %1 ] && echo %1' List | ...
495 11$ parallel '[ -f {} ] && echo {}' < List | ...
497 https://web.archive.org/web/20160702211113/
499 http://carrera.databits.net/~ksb/msrc/local/bin/xapply/xapply.html
500 DIFFERENCES BETWEEN AIX apply AND GNU Parallel
502 apply can build command lines based on a template and arguments - very
503 much like GNU parallel. apply does not run jobs in parallel. apply does
504 not use an argument separator (like :::); instead the template must be
505 the first argument.
506 EXAMPLES FROM IBM's KNOWLEDGE CENTER
508 Here are the examples from IBM's Knowledge Center and the corresponding
510 command using GNU parallel:
511 To obtain results similar to those of the ls command, enter:
513 1$ apply echo *
515 1$ parallel echo ::: *
516 To compare the file named a1 to the file named b1, and the file named
518 a2 to the file named b2, enter:
519 2$ apply -2 cmp a1 b1 a2 b2
521 2$ parallel -N2 cmp ::: a1 b1 a2 b2
522 To run the who command five times, enter:
524 3$ apply -0 who 1 2 3 4 5
526 3$ parallel -N0 who ::: 1 2 3 4 5
527 To link all files in the current directory to the directory /usr/joe,
529 enter:
530 4$ apply 'ln %1 /usr/joe' *
532 4$ parallel ln {} /usr/joe ::: *
533 https://www-01.ibm.com/support/knowledgecenter/
535 ssw_aix_71/com.ibm.aix.cmds1/apply.htm (Last checked: 2019-01)
536 DIFFERENCES BETWEEN paexec AND GNU Parallel
538 paexec can run jobs in parallel on both the local and remote computers.
539 paexec requires commands to print a blank line as the last output. This
541 means you will have to write a wrapper for most programs.
542 paexec has a job dependency facility so a job can depend on another job
544 to be executed successfully. Sort of a poor-man's make.
545 EXAMPLES FROM paexec's EXAMPLE CATALOG
547 Here are the examples from paexec's example catalog with the equivalent
549 using GNU parallel:
550 1_div_X_run
552 1$ ../../paexec -s -l -c "`pwd`/1_div_X_cmd" -n +1 <<EOF [...]
554 1$ parallel echo {} '|' `pwd`/1_div_X_cmd <<EOF [...]
556 all_substr_run
558 2$ ../../paexec -lp -c "`pwd`/all_substr_cmd" -n +3 <<EOF [...]
560 2$ parallel echo {} '|' `pwd`/all_substr_cmd <<EOF [...]
562 cc_wrapper_run
564 3$ ../../paexec -c "env CC=gcc CFLAGS=-O2 `pwd`/cc_wrapper_cmd" \
566 -n 'host1 host2' \
567 -t '/usr/bin/ssh -x' <<EOF [...]
568 3$ parallel echo {} '|' "env CC=gcc CFLAGS=-O2 `pwd`/cc_wrapper_cmd" \
570 -S host1,host2 <<EOF [...]
571 # This is not exactly the same, but avoids the wrapper
573 parallel gcc -O2 -c -o {.}.o {} \
574 -S host1,host2 <<EOF [...]
575 toupper_run
577 4$ ../../paexec -lp -c "`pwd`/toupper_cmd" -n +10 <<EOF [...]
579 4$ parallel echo {} '|' ./toupper_cmd <<EOF [...]
581 # Without the wrapper:
583 parallel echo {} '| awk {print\ toupper\(\$0\)}' <<EOF [...]
584 https://github.com/cheusov/paexec
586 DIFFERENCES BETWEEN map(sitaramc) AND GNU Parallel
588 Summary table (see legend above): I1 - - I4 - - (I7) M1 (M2) M3 (M4) M5
589 M6 - O2 O3 - O5 - - N/A N/A O10 E1 - - - - - - - - - - - - - - - - -
590 (I7): Only under special circumstances. See below.
592 (M2+M4): Only if there is a single replacement string.
594 map rejects input with special characters:
596 echo "The Cure" > My\ brother\'s\ 12\"\ records
598 ls | map 'echo %; wc %'
600 It works with GNU parallel:
602 ls | parallel 'echo {}; wc {}'
604 Under some circumstances it also works with map:
606 ls | map 'echo % works %'
608 But tiny changes make it reject the input with special characters:
610 ls | map 'echo % does not work "%"'
612 This means that many UTF-8 characters will be rejected. This is by
614 design. From the web page: "As such, programs that quietly handle them,
615 with no warnings at all, are doing their users a disservice."
616 map delays each job by 0.01 s. This can be emulated by using parallel
618 --delay 0.01.
619 map prints '+' on stderr when a job starts, and '-' when a job
621 finishes. This cannot be disabled. parallel has --bar if you need to
622 see progress.
623 map's replacement strings (% %D %B %E) can be simulated in GNU parallel
625 by putting this in ~/.parallel/config:
626 --rpl '%'
628 --rpl '%D $_=Q(::dirname($_));'
629 --rpl '%B s:.*/::;s:\.[^/.]+$::;'
630 --rpl '%E s:.*\.::'
631 map does not have an argument separator on the command line, but uses
633 the first argument as command. This makes quoting harder which again
634 may affect readability. Compare:
635 map -p 2 'perl -ne '"'"'/^\S+\s+\S+$/ and print $ARGV,"\n"'"'" *
637 parallel -q perl -ne '/^\S+\s+\S+$/ and print $ARGV,"\n"' ::: *
639 map can do multiple arguments with context replace, but not without
641 context replace:
642 parallel --xargs echo 'BEGIN{'{}'}END' ::: 1 2 3
644 map "echo 'BEGIN{'%'}END'" 1 2 3
646 map has no support for grouping. So this gives the wrong results:
648 parallel perl -e '\$a=\"1{}\"x10000000\;print\ \$a,\"\\n\"' '>' {} \
650 ::: a b c d e f
651 ls -l a b c d e f
652 parallel -kP4 -n1 grep 1 ::: a b c d e f > out.par
653 map -n1 -p 4 'grep 1' a b c d e f > out.map-unbuf
654 map -n1 -p 4 'grep --line-buffered 1' a b c d e f > out.map-linebuf
655 map -n1 -p 1 'grep --line-buffered 1' a b c d e f > out.map-serial
656 ls -l out*
657 md5sum out*
658 EXAMPLES FROM map's WEBSITE
660 Here are the examples from map's web page with the equivalent using GNU
662 parallel:
663 1$ ls *.gif | map convert % %B.png # default max-args: 1
665 1$ ls *.gif | parallel convert {} {.}.png
667 2$ map "mkdir %B; tar -C %B -xf %" *.tgz # default max-args: 1
669 2$ parallel 'mkdir {.}; tar -C {.} -xf {}' ::: *.tgz
671 3$ ls *.gif | map cp % /tmp # default max-args: 100
673 3$ ls *.gif | parallel -X cp {} /tmp
675 4$ ls *.tar | map -n 1 tar -xf %
677 4$ ls *.tar | parallel tar -xf
679 5$ map "cp % /tmp" *.tgz
681 5$ parallel cp {} /tmp ::: *.tgz
683 6$ map "du -sm /home/%/mail" alice bob carol
685 6$ parallel "du -sm /home/{}/mail" ::: alice bob carol
687 or if you prefer running a single job with multiple args:
688 6$ parallel -Xj1 "du -sm /home/{}/mail" ::: alice bob carol
689 7$ cat /etc/passwd | map -d: 'echo user %1 has shell %7'
691 7$ cat /etc/passwd | parallel --colsep : 'echo user {1} has shell {7}'
693 8$ export MAP_MAX_PROCS=$(( `nproc` / 2 ))
695 8$ export PARALLEL=-j50%
697 https://github.com/sitaramc/map (Last checked: 2020-05)
699 DIFFERENCES BETWEEN ladon AND GNU Parallel
701 ladon can run multiple jobs on files in parallel.
702 ladon only works on files and the only way to specify files is using a
704 quoted glob string (such as \*.jpg). It is not possible to list the
705 files manually.
706 As replacement strings it uses FULLPATH DIRNAME BASENAME EXT RELDIR
708 RELPATH
709 These can be simulated using GNU parallel by putting this in
711 ~/.parallel/config:
712 --rpl 'FULLPATH $_=Q($_);chomp($_=qx{readlink -f $_});'
714 --rpl 'DIRNAME $_=Q(::dirname($_));chomp($_=qx{readlink -f $_});'
715 --rpl 'BASENAME s:.*/::;s:\.[^/.]+$::;'
716 --rpl 'EXT s:.*\.::'
717 --rpl 'RELDIR $_=Q($_);chomp(($_,$c)=qx{readlink -f $_;pwd});
718 s:\Q$c/\E::;$_=::dirname($_);'
719 --rpl 'RELPATH $_=Q($_);chomp(($_,$c)=qx{readlink -f $_;pwd});
720 s:\Q$c/\E::;'
721 ladon deals badly with filenames containing " and newline, and it fails
723 for output larger than 200k:
724 ladon '*' -- seq 36000 | wc
726 EXAMPLES FROM ladon MANUAL
728 It is assumed that the '--rpl's above are put in ~/.parallel/config and
730 that it is run under a shell that supports '**' globbing (such as zsh):
731 1$ ladon "**/*.txt" -- echo RELPATH
733 1$ parallel echo RELPATH ::: **/*.txt
735 2$ ladon "~/Documents/**/*.pdf" -- shasum FULLPATH >hashes.txt
737 2$ parallel shasum FULLPATH ::: ~/Documents/**/*.pdf >hashes.txt
739 3$ ladon -m thumbs/RELDIR "**/*.jpg" -- convert FULLPATH \
741 -thumbnail 100x100^ -gravity center -extent 100x100 \
742 thumbs/RELPATH
743 3$ parallel mkdir -p thumbs/RELDIR\; convert FULLPATH
745 -thumbnail 100x100^ -gravity center -extent 100x100 \
746 thumbs/RELPATH ::: **/*.jpg
747 4$ ladon "~/Music/*.wav" -- lame -V 2 FULLPATH DIRNAME/BASENAME.mp3
749 4$ parallel lame -V 2 FULLPATH DIRNAME/BASENAME.mp3 ::: ~/Music/*.wav
751 https://github.com/danielgtaylor/ladon (Last checked: 2019-01)
753 DIFFERENCES BETWEEN jobflow AND GNU Parallel
755 jobflow can run multiple jobs in parallel.
756 Just like xargs output from jobflow jobs running in parallel mix
758 together by default. jobflow can buffer into files (placed in
759 /run/shm), but these are not cleaned up if jobflow dies unexpectedly
760 (e.g. by Ctrl-C). If the total output is big (in the order of RAM+swap)
761 it can cause the system to slow to a crawl and eventually run out of
762 memory.
763 jobflow gives no error if the command is unknown, and like xargs
765 redirection and composed commands require wrapping with bash -c.
766 Input lines can at most be 4096 bytes. You can at most have 16 {}'s in
768 the command template. More than that either crashes the program or
769 simple does not execute the command.
770 jobflow has no equivalent for --pipe, or --sshlogin.
772 jobflow makes it possible to set resource limits on the running jobs.
774 This can be emulated by GNU parallel using bash's ulimit:
775 jobflow -limits=mem=100M,cpu=3,fsize=20M,nofiles=300 myjob
777 parallel 'ulimit -v 102400 -t 3 -f 204800 -n 300 myjob'
779 EXAMPLES FROM jobflow README
781 1$ cat things.list | jobflow -threads=8 -exec ./mytask {}
783 1$ cat things.list | parallel -j8 ./mytask {}
785 2$ seq 100 | jobflow -threads=100 -exec echo {}
787 2$ seq 100 | parallel -j100 echo {}
789 3$ cat urls.txt | jobflow -threads=32 -exec wget {}
791 3$ cat urls.txt | parallel -j32 wget {}
793 4$ find . -name '*.bmp' | \
795 jobflow -threads=8 -exec bmp2jpeg {.}.bmp {.}.jpg
796 4$ find . -name '*.bmp' | \
798 parallel -j8 bmp2jpeg {.}.bmp {.}.jpg
799 https://github.com/rofl0r/jobflow
801 DIFFERENCES BETWEEN gargs AND GNU Parallel
803 gargs can run multiple jobs in parallel.
804 Older versions cache output in memory. This causes it to be extremely
806 slow when the output is larger than the physical RAM, and can cause the
807 system to run out of memory.
808 See more details on this in man parallel_design.
810 Newer versions cache output in files, but leave files in $TMPDIR if it
812 is killed.
813 Output to stderr (standard error) is changed if the command fails.
815 EXAMPLES FROM gargs WEBSITE
817 1$ seq 12 -1 1 | gargs -p 4 -n 3 "sleep {0}; echo {1} {2}"
819 1$ seq 12 -1 1 | parallel -P 4 -n 3 "sleep {1}; echo {2} {3}"
821 2$ cat t.txt | gargs --sep "\s+" \
823 -p 2 "echo '{0}:{1}-{2}' full-line: \'{}\'"
824 2$ cat t.txt | parallel --colsep "\\s+" \
826 -P 2 "echo '{1}:{2}-{3}' full-line: \'{}\'"
827 https://github.com/brentp/gargs
829 DIFFERENCES BETWEEN orgalorg AND GNU Parallel
831 orgalorg can run the same job on multiple machines. This is related to
832 --onall and --nonall.
833 orgalorg supports entering the SSH password - provided it is the same
835 for all servers. GNU parallel advocates using ssh-agent instead, but it
836 is possible to emulate orgalorg's behavior by setting SSHPASS and by
837 using --ssh "sshpass ssh".
838 To make the emulation easier, make a simple alias:
840 alias par_emul="parallel -j0 --ssh 'sshpass ssh' --nonall --tag --lb"
842 If you want to supply a password run:
844 SSHPASS=`ssh-askpass`
846 or set the password directly:
848 SSHPASS=P4$$w0rd!
850 If the above is set up you can then do:
852 orgalorg -o frontend1 -o frontend2 -p -C uptime
854 par_emul -S frontend1 -S frontend2 uptime
855 orgalorg -o frontend1 -o frontend2 -p -C top -bid 1
857 par_emul -S frontend1 -S frontend2 top -bid 1
858 orgalorg -o frontend1 -o frontend2 -p -er /tmp -n \
860 'md5sum /tmp/bigfile' -S bigfile
861 par_emul -S frontend1 -S frontend2 --basefile bigfile \
862 --workdir /tmp md5sum /tmp/bigfile
863 orgalorg has a progress indicator for the transferring of a file. GNU
865 parallel does not.
866 https://github.com/reconquest/orgalorg
868 DIFFERENCES BETWEEN Rust parallel AND GNU Parallel
870 Rust parallel focuses on speed. It is almost as fast as xargs. It
871 implements a few features from GNU parallel, but lacks many functions.
872 All these fail:
873 # Read arguments from file
875 parallel -a file echo
876 # Changing the delimiter
877 parallel -d _ echo ::: a_b_c_
878 These do something different from GNU parallel
880 # -q to protect quoted $ and space
882 parallel -q perl -e '$a=shift; print "$a"x10000000' ::: a b c
883 # Generation of combination of inputs
884 parallel echo {1} {2} ::: red green blue ::: S M L XL XXL
885 # {= perl expression =} replacement string
886 parallel echo '{= s/new/old/ =}' ::: my.new your.new
887 # --pipe
888 seq 100000 | parallel --pipe wc
889 # linked arguments
890 parallel echo ::: S M L :::+ sml med lrg ::: R G B :::+ red grn blu
891 # Run different shell dialects
892 zsh -c 'parallel echo \={} ::: zsh && true'
893 csh -c 'parallel echo \$\{\} ::: shell && true'
894 bash -c 'parallel echo \$\({}\) ::: pwd && true'
895 # Rust parallel does not start before the last argument is read
896 (seq 10; sleep 5; echo 2) | time parallel -j2 'sleep 2; echo'
897 tail -f /var/log/syslog | parallel echo
898 Most of the examples from the book GNU Parallel 2018 do not work, thus
900 Rust parallel is not close to being a compatible replacement.
901 Rust parallel has no remote facilities.
903 It uses /tmp/parallel for tmp files and does not clean up if terminated
905 abruptly. If another user on the system uses Rust parallel, then
906 /tmp/parallel will have the wrong permissions and Rust parallel will
907 fail. A malicious user can setup the right permissions and symlink the
908 output file to one of the user's files and next time the user uses Rust
909 parallel it will overwrite this file.
910 attacker$ mkdir /tmp/parallel
912 attacker$ chmod a+rwX /tmp/parallel
913 # Symlink to the file the attacker wants to zero out
914 attacker$ ln -s ~victim/.important-file /tmp/parallel/stderr_1
915 victim$ seq 1000 | parallel echo
916 # This file is now overwritten with stderr from 'echo'
917 victim$ cat ~victim/.important-file
918 If /tmp/parallel runs full during the run, Rust parallel does not
920 report this, but finishes with success - thereby risking data loss.
921 https://github.com/mmstick/parallel
923 DIFFERENCES BETWEEN Rush AND GNU Parallel
925 rush (https://github.com/shenwei356/rush) is written in Go and based on
926 gargs.
927 Just like GNU parallel rush buffers in temporary files. But opposite
929 GNU parallel rush does not clean up, if the process dies abnormally.
930 rush has some string manipulations that can be emulated by putting this
932 into ~/.parallel/config (/ is used instead of %, and % is used instead
933 of ^ as that is closer to bash's ${var%postfix}):
934 --rpl '{:} s:(\.[^/]+)*$::'
936 --rpl '{:%([^}]+?)} s:$$1(\.[^/]+)*$::'
937 --rpl '{/:%([^}]*?)} s:.*/(.*)$$1(\.[^/]+)*$:$1:'
938 --rpl '{/:} s:(.*/)?([^/.]+)(\.[^/]+)*$:$2:'
939 --rpl '{@(.*?)} /$$1/ and $_=$1;'
940 EXAMPLES FROM rush's WEBSITE
942 Here are the examples from rush's website with the equivalent command
944 in GNU parallel.
945 1. Simple run, quoting is not necessary
947 $ seq 1 3 | rush echo {}
949 $ seq 1 3 | parallel echo {}
951 2. Read data from file (`-i`)
953 $ rush echo {} -i data1.txt -i data2.txt
955 $ cat data1.txt data2.txt | parallel echo {}
957 3. Keep output order (`-k`)
959 $ seq 1 3 | rush 'echo {}' -k
961 $ seq 1 3 | parallel -k echo {}
963 4. Timeout (`-t`)
965 $ time seq 1 | rush 'sleep 2; echo {}' -t 1
967 $ time seq 1 | parallel --timeout 1 'sleep 2; echo {}'
969 5. Retry (`-r`)
971 $ seq 1 | rush 'python unexisted_script.py' -r 1
973 $ seq 1 | parallel --retries 2 'python unexisted_script.py'
975 Use -u to see it is really run twice:
977 $ seq 1 | parallel -u --retries 2 'python unexisted_script.py'
979 6. Dirname (`{/}`) and basename (`{%}`) and remove custom suffix
981 (`{^suffix}`)
982 $ echo dir/file_1.txt.gz | rush 'echo {/} {%} {^_1.txt.gz}'
984 $ echo dir/file_1.txt.gz |
986 parallel --plus echo {//} {/} {%_1.txt.gz}
987 7. Get basename, and remove last (`{.}`) or any (`{:}`) extension
989 $ echo dir.d/file.txt.gz | rush 'echo {.} {:} {%.} {%:}'
991 $ echo dir.d/file.txt.gz | parallel 'echo {.} {:} {/.} {/:}'
993 8. Job ID, combine fields index and other replacement strings
995 $ echo 12 file.txt dir/s_1.fq.gz |
997 rush 'echo job {#}: {2} {2.} {3%:^_1}'
998 $ echo 12 file.txt dir/s_1.fq.gz |
1000 parallel --colsep ' ' 'echo job {#}: {2} {2.} {3/:%_1}'
1001 9. Capture submatch using regular expression (`{@regexp}`)
1003 $ echo read_1.fq.gz | rush 'echo {@(.+)_\d}'
1005 $ echo read_1.fq.gz | parallel 'echo {@(.+)_\d}'
1007 10. Custom field delimiter (`-d`)
1009 $ echo a=b=c | rush 'echo {1} {2} {3}' -d =
1011 $ echo a=b=c | parallel -d = echo {1} {2} {3}
1013 11. Send multi-lines to every command (`-n`)
1015 $ seq 5 | rush -n 2 -k 'echo "{}"; echo'
1017 $ seq 5 |
1019 parallel -n 2 -k \
1020 'echo {=-1 $_=join"\n",@arg[1..$#arg] =}; echo'
1021 $ seq 5 | rush -n 2 -k 'echo "{}"; echo' -J ' '
1023 $ seq 5 | parallel -n 2 -k 'echo {}; echo'
1025 12. Custom record delimiter (`-D`), note that empty records are not
1027 used.
1028 $ echo a b c d | rush -D " " -k 'echo {}'
1030 $ echo a b c d | parallel -d " " -k 'echo {}'
1032 $ echo abcd | rush -D "" -k 'echo {}'
1034 Cannot be done by GNU Parallel
1036 $ cat fasta.fa
1038 >seq1
1039 tag
1040 >seq2
1041 cat
1042 gat
1043 >seq3
1044 attac
1045 a
1046 cat
1047 $ cat fasta.fa | rush -D ">" \
1049 'echo FASTA record {#}: name: {1} sequence: {2}' -k -d "\n"
1050 # rush fails to join the multiline sequences
1051 $ cat fasta.fa | (read -n1 ignore_first_char;
1053 parallel -d '>' --colsep '\n' echo FASTA record {#}: \
1054 name: {1} sequence: '{=2 $_=join"",@arg[2..$#arg]=}'
1055 )
1056 13. Assign value to variable, like `awk -v` (`-v`)
1058 $ seq 1 |
1060 rush 'echo Hello, {fname} {lname}!' -v fname=Wei -v lname=Shen
1061 $ seq 1 |
1063 parallel -N0 \
1064 'fname=Wei; lname=Shen; echo Hello, ${fname} ${lname}!'
1065 $ for var in a b; do \
1067 $ seq 1 3 | rush -k -v var=$var 'echo var: {var}, data: {}'; \
1068 $ done
1069 In GNU parallel you would typically do:
1071 $ seq 1 3 | parallel -k echo var: {1}, data: {2} ::: a b :::: -
1073 If you really want the var:
1075 $ seq 1 3 |
1077 parallel -k var={1} ';echo var: $var, data: {}' ::: a b :::: -
1078 If you really want the for-loop:
1080 $ for var in a b; do
1082 > export var;
1083 > seq 1 3 | parallel -k 'echo var: $var, data: {}';
1084 > done
1085 Contrary to rush this also works if the value is complex like:
1087 My brother's 12" records
1089 14. Preset variable (`-v`), avoid repeatedly writing verbose
1091 replacement strings
1092 # naive way
1094 $ echo read_1.fq.gz | rush 'echo {:^_1} {:^_1}_2.fq.gz'
1095 $ echo read_1.fq.gz | parallel 'echo {:%_1} {:%_1}_2.fq.gz'
1097 # macro + removing suffix
1099 $ echo read_1.fq.gz |
1100 rush -v p='{:^_1}' 'echo {p} {p}_2.fq.gz'
1101 $ echo read_1.fq.gz |
1103 parallel 'p={:%_1}; echo $p ${p}_2.fq.gz'
1104 # macro + regular expression
1106 $ echo read_1.fq.gz | rush -v p='{@(.+?)_\d}' 'echo {p} {p}_2.fq.gz'
1107 $ echo read_1.fq.gz | parallel 'p={@(.+?)_\d}; echo $p ${p}_2.fq.gz'
1109 Contrary to rush GNU parallel works with complex values:
1111 echo "My brother's 12\"read_1.fq.gz" |
1113 parallel 'p={@(.+?)_\d}; echo $p ${p}_2.fq.gz'
1114 15. Interrupt jobs by `Ctrl-C`, rush will stop unfinished commands and
1116 exit.
1117 $ seq 1 20 | rush 'sleep 1; echo {}'
1119 ^C
1120 $ seq 1 20 | parallel 'sleep 1; echo {}'
1122 ^C
1123 16. Continue/resume jobs (`-c`). When some jobs failed (by execution
1125 failure, timeout, or canceling by user with `Ctrl + C`), please switch
1126 flag `-c/--continue` on and run again, so that `rush` can save
1127 successful commands and ignore them in NEXT run.
1128 $ seq 1 3 | rush 'sleep {}; echo {}' -t 3 -c
1130 $ cat successful_cmds.rush
1131 $ seq 1 3 | rush 'sleep {}; echo {}' -t 3 -c
1132 $ seq 1 3 | parallel --joblog mylog --timeout 2 \
1134 'sleep {}; echo {}'
1135 $ cat mylog
1136 $ seq 1 3 | parallel --joblog mylog --retry-failed \
1137 'sleep {}; echo {}'
1138 Multi-line jobs:
1140 $ seq 1 3 | rush 'sleep {}; echo {}; \
1142 echo finish {}' -t 3 -c -C finished.rush
1143 $ cat finished.rush
1144 $ seq 1 3 | rush 'sleep {}; echo {}; \
1145 echo finish {}' -t 3 -c -C finished.rush
1146 $ seq 1 3 |
1148 parallel --joblog mylog --timeout 2 'sleep {}; echo {}; \
1149 echo finish {}'
1150 $ cat mylog
1151 $ seq 1 3 |
1152 parallel --joblog mylog --retry-failed 'sleep {}; echo {}; \
1153 echo finish {}'
1154 17. A comprehensive example: downloading 1K+ pages given by three URL
1156 list files using `phantomjs save_page.js` (some page contents are
1157 dynamically generated by Javascript, so `wget` does not work). Here I
1158 set max jobs number (`-j`) as `20`, each job has a max running time
1159 (`-t`) of `60` seconds and `3` retry changes (`-r`). Continue flag `-c`
1160 is also switched on, so we can continue unfinished jobs. Luckily, it's
1161 accomplished in one run :)
1162 $ for f in $(seq 2014 2016); do \
1164 $ /bin/rm -rf $f; mkdir -p $f; \
1165 $ cat $f.html.txt | rush -v d=$f -d = \
1166 'phantomjs save_page.js "{}" > {d}/{3}.html' \
1167 -j 20 -t 60 -r 3 -c; \
1168 $ done
1169 GNU parallel can append to an existing joblog with '+':
1171 $ rm mylog
1173 $ for f in $(seq 2014 2016); do
1174 /bin/rm -rf $f; mkdir -p $f;
1175 cat $f.html.txt |
1176 parallel -j20 --timeout 60 --retries 4 --joblog +mylog \
1177 --colsep = \
1178 phantomjs save_page.js {1}={2}={3} '>' $f/{3}.html
1179 done
1180 18. A bioinformatics example: mapping with `bwa`, and processing result
1182 with `samtools`:
1183 $ ref=ref/xxx.fa
1185 $ threads=25
1186 $ ls -d raw.cluster.clean.mapping/* \
1187 | rush -v ref=$ref -v j=$threads -v p='{}/{%}' \
1188 'bwa mem -t {j} -M -a {ref} {p}_1.fq.gz {p}_2.fq.gz >{p}.sam;\
1189 samtools view -bS {p}.sam > {p}.bam; \
1190 samtools sort -T {p}.tmp -@ {j} {p}.bam -o {p}.sorted.bam; \
1191 samtools index {p}.sorted.bam; \
1192 samtools flagstat {p}.sorted.bam > {p}.sorted.bam.flagstat; \
1193 /bin/rm {p}.bam {p}.sam;' \
1194 -j 2 --verbose -c -C mapping.rush
1195 GNU parallel would use a function:
1197 $ ref=ref/xxx.fa
1199 $ export ref
1200 $ thr=25
1201 $ export thr
1202 $ bwa_sam() {
1203 p="$1"
1204 bam="$p".bam
1205 sam="$p".sam
1206 sortbam="$p".sorted.bam
1207 bwa mem -t $thr -M -a $ref ${p}_1.fq.gz ${p}_2.fq.gz > "$sam"
1208 samtools view -bS "$sam" > "$bam"
1209 samtools sort -T ${p}.tmp -@ $thr "$bam" -o "$sortbam"
1210 samtools index "$sortbam"
1211 samtools flagstat "$sortbam" > "$sortbam".flagstat
1212 /bin/rm "$bam" "$sam"
1213 }
1214 $ export -f bwa_sam
1215 $ ls -d raw.cluster.clean.mapping/* |
1216 parallel -j 2 --verbose --joblog mylog bwa_sam
1217 Other rush features
1219 rush has:
1221 · awk -v like custom defined variables (-v)
1223 With GNU parallel you would simply set a shell variable:
1225 parallel 'v={}; echo "$v"' ::: foo
1227 echo foo | rush -v v={} 'echo {v}'
1228 Also rush does not like special chars. So these do not work:
1230 echo does not work | rush -v v=\" 'echo {v}'
1232 echo "My brother's 12\" records" | rush -v v={} 'echo {v}'
1233 Whereas the corresponding GNU parallel version works:
1235 parallel 'v=\"; echo "$v"' ::: works
1237 parallel 'v={}; echo "$v"' ::: "My brother's 12\" records"
1238 · Exit on first error(s) (-e)
1240 This is called --halt now,fail=1 (or shorter: --halt 2) when used
1242 with GNU parallel.
1243 · Settable records sending to every command (-n, default 1)
1245 This is also called -n in GNU parallel.
1247 · Practical replacement strings
1249 {:} remove any extension
1251 With GNU parallel this can be emulated by:
1252 parallel --plus echo '{/\..*/}' ::: foo.ext.bar.gz
1254 {^suffix}, remove suffix
1256 With GNU parallel this can be emulated by:
1257 parallel --plus echo '{%.bar.gz}' ::: foo.ext.bar.gz
1259 {@regexp}, capture submatch using regular expression
1261 With GNU parallel this can be emulated by:
1262 parallel --rpl '{@(.*?)} /$$1/ and $_=$1;' \
1264 echo '{@\d_(.*).gz}' ::: 1_foo.gz
1265 {%.}, {%:}, basename without extension
1267 With GNU parallel this can be emulated by:
1268 parallel echo '{= s:.*/::;s/\..*// =}' ::: dir/foo.bar.gz
1270 And if you need it often, you define a --rpl in
1272 $HOME/.parallel/config:
1273 --rpl '{%.} s:.*/::;s/\..*//'
1275 --rpl '{%:} s:.*/::;s/\..*//'
1276 Then you can use them as:
1278 parallel echo {%.} {%:} ::: dir/foo.bar.gz
1280 · Preset variable (macro)
1282 E.g.
1284 echo foosuffix | rush -v p={^suffix} 'echo {p}_new_suffix'
1286 With GNU parallel this can be emulated by:
1288 echo foosuffix |
1290 parallel --plus 'p={%suffix}; echo ${p}_new_suffix'
1291 Opposite rush GNU parallel works fine if the input contains double
1293 space, ' and ":
1294 echo "1'6\" foosuffix" |
1296 parallel --plus 'p={%suffix}; echo "${p}"_new_suffix'
1297 · Commands of multi-lines
1299 While you can use multi-lined commands in GNU parallel, to improve
1301 readability GNU parallel discourages the use of multi-line
1302 commands. In most cases it can be written as a function:
1303 seq 1 3 |
1305 parallel --timeout 2 --joblog my.log 'sleep {}; echo {}; \
1306 echo finish {}'
1307 Could be written as:
1309 doit() {
1311 sleep "$1"
1312 echo "$1"
1313 echo finish "$1"
1314 }
1315 export -f doit
1316 seq 1 3 | parallel --timeout 2 --joblog my.log doit
1317 The failed commands can be resumed with:
1319 seq 1 3 |
1321 parallel --resume-failed --joblog my.log 'sleep {}; echo {};\
1322 echo finish {}'
1323 https://github.com/shenwei356/rush
1325 DIFFERENCES BETWEEN ClusterSSH AND GNU Parallel
1327 ClusterSSH solves a different problem than GNU parallel.
1328 ClusterSSH opens a terminal window for each computer and using a master
1330 window you can run the same command on all the computers. This is
1331 typically used for administrating several computers that are almost
1332 identical.
1333 GNU parallel runs the same (or different) commands with different
1335 arguments in parallel possibly using remote computers to help
1336 computing. If more than one computer is listed in -S GNU parallel may
1337 only use one of these (e.g. if there are 8 jobs to be run and one
1338 computer has 8 cores).
1339 GNU parallel can be used as a poor-man's version of ClusterSSH:
1341 parallel --nonall -S server-a,server-b do_stuff foo bar
1343 https://github.com/duncs/clusterssh
1345 DIFFERENCES BETWEEN coshell AND GNU Parallel
1347 coshell only accepts full commands on standard input. Any quoting needs
1348 to be done by the user.
1349 Commands are run in sh so any bash/tcsh/zsh specific syntax will not
1351 work.
1352 Output can be buffered by using -d. Output is buffered in memory, so
1354 big output can cause swapping and therefore be terrible slow or even
1355 cause out of memory.
1356 https://github.com/gdm85/coshell (Last checked: 2019-01)
1358 DIFFERENCES BETWEEN spread AND GNU Parallel
1360 spread runs commands on all directories.
1361 It can be emulated with GNU parallel using this Bash function:
1363 spread() {
1365 _cmds() {
1366 perl -e '$"=" && ";print "@ARGV"' "cd {}" "$@"
1367 }
1368 parallel $(_cmds "$@")'|| echo exit status $?' ::: */
1369 }
1370 This works except for the --exclude option.
1372 (Last checked: 2017-11)
1374 DIFFERENCES BETWEEN pyargs AND GNU Parallel
1376 pyargs deals badly with input containing spaces. It buffers stdout, but
1377 not stderr. It buffers in RAM. {} does not work as replacement string.
1378 It does not support running functions.
1379 pyargs does not support composed commands if run with --lines, and
1381 fails on pyargs traceroute gnu.org fsf.org.
1382 Examples
1384 seq 5 | pyargs -P50 -L seq
1386 seq 5 | parallel -P50 --lb seq
1387 seq 5 | pyargs -P50 --mark -L seq
1389 seq 5 | parallel -P50 --lb \
1390 --tagstring OUTPUT'[{= $_=$job->replaced()=}]' seq
1391 # Similar, but not precisely the same
1392 seq 5 | parallel -P50 --lb --tag seq
1393 seq 5 | pyargs -P50 --mark command
1395 # Somewhat longer with GNU Parallel due to the special
1396 # --mark formatting
1397 cmd="$(echo "command" | parallel --shellquote)"
1398 wrap_cmd() {
1399 echo "MARK $cmd $@================================" >&3
1400 echo "OUTPUT START[$cmd $@]:"
1401 eval $cmd "$@"
1402 echo "OUTPUT END[$cmd $@]"
1403 }
1404 (seq 5 | env_parallel -P2 wrap_cmd) 3>&1
1405 # Similar, but not exactly the same
1406 seq 5 | parallel -t --tag command
1407 (echo '1 2 3';echo 4 5 6) | pyargs --stream seq
1409 (echo '1 2 3';echo 4 5 6) | perl -pe 's/\n/ /' |
1410 parallel -r -d' ' seq
1411 # Similar, but not exactly the same
1412 parallel seq ::: 1 2 3 4 5 6
1413 https://github.com/robertblackwell/pyargs (Last checked: 2019-01)
1415 DIFFERENCES BETWEEN concurrently AND GNU Parallel
1417 concurrently runs jobs in parallel.
1418 The output is prepended with the job number, and may be incomplete:
1420 $ concurrently 'seq 100000' | (sleep 3;wc -l)
1422 7165
1423 When pretty printing it caches output in memory. Output mixes by using
1425 test MIX below whether or not output is cached.
1426 There seems to be no way of making a template command and have
1428 concurrently fill that with different args. The full commands must be
1429 given on the command line.
1430 There is also no way of controlling how many jobs should be run in
1432 parallel at a time - i.e. "number of jobslots". Instead all jobs are
1433 simply started in parallel.
1434 https://github.com/kimmobrunfeldt/concurrently (Last checked: 2019-01)
1436 DIFFERENCES BETWEEN map(soveran) AND GNU Parallel
1438 map does not run jobs in parallel by default. The README suggests
1439 using:
1440 ... | map t 'sleep $t && say done &'
1442 But this fails if more jobs are run in parallel than the number of
1444 available processes. Since there is no support for parallelization in
1445 map itself, the output also mixes:
1446 seq 10 | map i 'echo start-$i && sleep 0.$i && echo end-$i &'
1448 The major difference is that GNU parallel is built for parallelization
1450 and map is not. So GNU parallel has lots of ways of dealing with the
1451 issues that parallelization raises:
1452 · Keep the number of processes manageable
1454 · Make sure output does not mix
1456 · Make Ctrl-C kill all running processes
1458 EXAMPLES FROM maps WEBSITE
1460 Here are the 5 examples converted to GNU Parallel:
1462 1$ ls *.c | map f 'foo $f'
1464 1$ ls *.c | parallel foo
1465 2$ ls *.c | map f 'foo $f; bar $f'
1467 2$ ls *.c | parallel 'foo {}; bar {}'
1468 3$ cat urls | map u 'curl -O $u'
1470 3$ cat urls | parallel curl -O
1471 4$ printf "1\n1\n1\n" | map t 'sleep $t && say done'
1473 4$ printf "1\n1\n1\n" | parallel 'sleep {} && say done'
1474 4$ parallel 'sleep {} && say done' ::: 1 1 1
1475 5$ printf "1\n1\n1\n" | map t 'sleep $t && say done &'
1477 5$ printf "1\n1\n1\n" | parallel -j0 'sleep {} && say done'
1478 5$ parallel -j0 'sleep {} && say done' ::: 1 1 1
1479 https://github.com/soveran/map (Last checked: 2019-01)
1481 DIFFERENCES BETWEEN loop AND GNU Parallel
1483 loop mixes stdout and stderr:
1484 loop 'ls /no-such-file' >/dev/null
1486 loop's replacement string $ITEM does not quote strings:
1488 echo 'two spaces' | loop 'echo $ITEM'
1490 loop cannot run functions:
1492 myfunc() { echo joe; }
1494 export -f myfunc
1495 loop 'myfunc this fails'
1496 EXAMPLES FROM loop's WEBSITE
1498 Some of the examples from https://github.com/Miserlou/Loop/ can be
1500 emulated with GNU parallel:
1501 # A couple of functions will make the code easier to read
1503 $ loopy() {
1504 yes | parallel -uN0 -j1 "$@"
1505 }
1506 $ export -f loopy
1507 $ time_out() {
1508 parallel -uN0 -q --timeout "$@" ::: 1
1509 }
1510 $ match() {
1511 perl -0777 -ne 'grep /'"$1"'/,$_ and print or exit 1'
1512 }
1513 $ export -f match
1514 $ loop 'ls' --every 10s
1516 $ loopy --delay 10s ls
1517 $ loop 'touch $COUNT.txt' --count-by 5
1519 $ loopy touch '{= $_=seq()*5 =}'.txt
1520 $ loop --until-contains 200 -- \
1522 ./get_response_code.sh --site mysite.biz`
1523 $ loopy --halt now,success=1 \
1524 './get_response_code.sh --site mysite.biz | match 200'
1525 $ loop './poke_server' --for-duration 8h
1527 $ time_out 8h loopy ./poke_server
1528 $ loop './poke_server' --until-success
1530 $ loopy --halt now,success=1 ./poke_server
1531 $ cat files_to_create.txt | loop 'touch $ITEM'
1533 $ cat files_to_create.txt | parallel touch {}
1534 $ loop 'ls' --for-duration 10min --summary
1536 # --joblog is somewhat more verbose than --summary
1537 $ time_out 10m loopy --joblog my.log ./poke_server; cat my.log
1538 $ loop 'echo hello'
1540 $ loopy echo hello
1541 $ loop 'echo $COUNT'
1543 # GNU Parallel counts from 1
1544 $ loopy echo {#}
1545 # Counting from 0 can be forced
1546 $ loopy echo '{= $_=seq()-1 =}'
1547 $ loop 'echo $COUNT' --count-by 2
1549 $ loopy echo '{= $_=2*(seq()-1) =}'
1550 $ loop 'echo $COUNT' --count-by 2 --offset 10
1552 $ loopy echo '{= $_=10+2*(seq()-1) =}'
1553 $ loop 'echo $COUNT' --count-by 1.1
1555 # GNU Parallel rounds 3.3000000000000003 to 3.3
1556 $ loopy echo '{= $_=1.1*(seq()-1) =}'
1557 $ loop 'echo $COUNT $ACTUALCOUNT' --count-by 2
1559 $ loopy echo '{= $_=2*(seq()-1) =} {#}'
1560 $ loop 'echo $COUNT' --num 3 --summary
1562 # --joblog is somewhat more verbose than --summary
1563 $ seq 3 | parallel --joblog my.log echo; cat my.log
1564 $ loop 'ls -foobarbatz' --num 3 --summary
1566 # --joblog is somewhat more verbose than --summary
1567 $ seq 3 | parallel --joblog my.log -N0 ls -foobarbatz; cat my.log
1568 $ loop 'echo $COUNT' --count-by 2 --num 50 --only-last
1570 # Can be emulated by running 2 jobs
1571 $ seq 49 | parallel echo '{= $_=2*(seq()-1) =}' >/dev/null
1572 $ echo 50| parallel echo '{= $_=2*(seq()-1) =}'
1573 $ loop 'date' --every 5s
1575 $ loopy --delay 5s date
1576 $ loop 'date' --for-duration 8s --every 2s
1578 $ time_out 8s loopy --delay 2s date
1579 $ loop 'date -u' --until-time '2018-05-25 20:50:00' --every 5s
1581 $ seconds=$((`date -d 2019-05-25T20:50:00 +%s` - `date +%s`))s
1582 $ time_out $seconds loopy --delay 5s date -u
1583 $ loop 'echo $RANDOM' --until-contains "666"
1585 $ loopy --halt now,success=1 'echo $RANDOM | match 666'
1586 $ loop 'if (( RANDOM % 2 )); then
1588 (echo "TRUE"; true);
1589 else
1590 (echo "FALSE"; false);
1591 fi' --until-success
1592 $ loopy --halt now,success=1 'if (( $RANDOM % 2 )); then
1593 (echo "TRUE"; true);
1594 else
1595 (echo "FALSE"; false);
1596 fi'
1597 $ loop 'if (( RANDOM % 2 )); then
1599 (echo "TRUE"; true);
1600 else
1601 (echo "FALSE"; false);
1602 fi' --until-error
1603 $ loopy --halt now,fail=1 'if (( $RANDOM % 2 )); then
1604 (echo "TRUE"; true);
1605 else
1606 (echo "FALSE"; false);
1607 fi'
1608 $ loop 'date' --until-match "(\d{4})"
1610 $ loopy --halt now,success=1 'date | match [0-9][0-9][0-9][0-9]'
1611 $ loop 'echo $ITEM' --for red,green,blue
1613 $ parallel echo ::: red green blue
1614 $ cat /tmp/my-list-of-files-to-create.txt | loop 'touch $ITEM'
1616 $ cat /tmp/my-list-of-files-to-create.txt | parallel touch
1617 $ ls | loop 'cp $ITEM $ITEM.bak'; ls
1619 $ ls | parallel cp {} {}.bak; ls
1620 $ loop 'echo $ITEM | tr a-z A-Z' -i
1622 $ parallel 'echo {} | tr a-z A-Z'
1623 # Or more efficiently:
1624 $ parallel --pipe tr a-z A-Z
1625 $ loop 'echo $ITEM' --for "`ls`"
1627 $ parallel echo {} ::: "`ls`"
1628 $ ls | loop './my_program $ITEM' --until-success;
1630 $ ls | parallel --halt now,success=1 ./my_program {}
1631 $ ls | loop './my_program $ITEM' --until-fail;
1633 $ ls | parallel --halt now,fail=1 ./my_program {}
1634 $ ./deploy.sh;
1636 loop 'curl -sw "%{http_code}" http://coolwebsite.biz' \
1637 --every 5s --until-contains 200;
1638 ./announce_to_slack.sh
1639 $ ./deploy.sh;
1640 loopy --delay 5s --halt now,success=1 \
1641 'curl -sw "%{http_code}" http://coolwebsite.biz | match 200';
1642 ./announce_to_slack.sh
1643 $ loop "ping -c 1 mysite.com" --until-success; ./do_next_thing
1645 $ loopy --halt now,success=1 ping -c 1 mysite.com; ./do_next_thing
1646 $ ./create_big_file -o my_big_file.bin;
1648 loop 'ls' --until-contains 'my_big_file.bin';
1649 ./upload_big_file my_big_file.bin
1650 # inotifywait is a better tool to detect file system changes.
1651 # It can even make sure the file is complete
1652 # so you are not uploading an incomplete file
1653 $ inotifywait -qmre MOVED_TO -e CLOSE_WRITE --format %w%f . |
1654 grep my_big_file.bin
1655 $ ls | loop 'cp $ITEM $ITEM.bak'
1657 $ ls | parallel cp {} {}.bak
1658 $ loop './do_thing.sh' --every 15s --until-success --num 5
1660 $ parallel --retries 5 --delay 15s ::: ./do_thing.sh
1661 https://github.com/Miserlou/Loop/ (Last checked: 2018-10)
1663 DIFFERENCES BETWEEN lorikeet AND GNU Parallel
1665 lorikeet can run jobs in parallel. It does this based on a dependency
1666 graph described in a file, so this is similar to make.
1667 https://github.com/cetra3/lorikeet (Last checked: 2018-10)
1669 DIFFERENCES BETWEEN spp AND GNU Parallel
1671 spp can run jobs in parallel. spp does not use a command template to
1672 generate the jobs, but requires jobs to be in a file. Output from the
1673 jobs mix.
1674 https://github.com/john01dav/spp (Last checked: 2019-01)
1676 DIFFERENCES BETWEEN paral AND GNU Parallel
1678 paral prints a lot of status information and stores the output from the
1679 commands run into files. This means it cannot be used the middle of a
1680 pipe like this
1681 paral "echo this" "echo does not" "echo work" | wc
1683 Instead it puts the output into files named like out_#_command.out.log.
1685 To get a very similar behaviour with GNU parallel use --results
1686 'out_{#}_{=s/[^\sa-z_0-9]//g;s/\s+/_/g=}.log' --eta
1687 paral only takes arguments on the command line and each argument should
1689 be a full command. Thus it does not use command templates.
1690 This limits how many jobs it can run in total, because they all need to
1692 fit on a single command line.
1693 paral has no support for running jobs remotely.
1695 EXAMPLES FROM README.markdown
1697 The examples from README.markdown and the corresponding command run
1699 with GNU parallel (--results
1700 'out_{#}_{=s/[^\sa-z_0-9]//g;s/\s+/_/g=}.log' --eta is omitted from the
1701 GNU parallel command):
1702 1$ paral "command 1" "command 2 --flag" "command arg1 arg2"
1704 1$ parallel ::: "command 1" "command 2 --flag" "command arg1 arg2"
1705 2$ paral "sleep 1 && echo c1" "sleep 2 && echo c2" \
1707 "sleep 3 && echo c3" "sleep 4 && echo c4" "sleep 5 && echo c5"
1708 2$ parallel ::: "sleep 1 && echo c1" "sleep 2 && echo c2" \
1709 "sleep 3 && echo c3" "sleep 4 && echo c4" "sleep 5 && echo c5"
1710 # Or shorter:
1711 parallel "sleep {} && echo c{}" ::: {1..5}
1712 3$ paral -n=0 "sleep 5 && echo c5" "sleep 4 && echo c4" \
1714 "sleep 3 && echo c3" "sleep 2 && echo c2" "sleep 1 && echo c1"
1715 3$ parallel ::: "sleep 5 && echo c5" "sleep 4 && echo c4" \
1716 "sleep 3 && echo c3" "sleep 2 && echo c2" "sleep 1 && echo c1"
1717 # Or shorter:
1718 parallel -j0 "sleep {} && echo c{}" ::: 5 4 3 2 1
1719 4$ paral -n=1 "sleep 5 && echo c5" "sleep 4 && echo c4" \
1721 "sleep 3 && echo c3" "sleep 2 && echo c2" "sleep 1 && echo c1"
1722 4$ parallel -j1 "sleep {} && echo c{}" ::: 5 4 3 2 1
1723 5$ paral -n=2 "sleep 5 && echo c5" "sleep 4 && echo c4" \
1725 "sleep 3 && echo c3" "sleep 2 && echo c2" "sleep 1 && echo c1"
1726 5$ parallel -j2 "sleep {} && echo c{}" ::: 5 4 3 2 1
1727 6$ paral -n=5 "sleep 5 && echo c5" "sleep 4 && echo c4" \
1729 "sleep 3 && echo c3" "sleep 2 && echo c2" "sleep 1 && echo c1"
1730 6$ parallel -j5 "sleep {} && echo c{}" ::: 5 4 3 2 1
1731 7$ paral -n=1 "echo a && sleep 0.5 && echo b && sleep 0.5 && \
1733 echo c && sleep 0.5 && echo d && sleep 0.5 && \
1734 echo e && sleep 0.5 && echo f && sleep 0.5 && \
1735 echo g && sleep 0.5 && echo h"
1736 7$ parallel ::: "echo a && sleep 0.5 && echo b && sleep 0.5 && \
1737 echo c && sleep 0.5 && echo d && sleep 0.5 && \
1738 echo e && sleep 0.5 && echo f && sleep 0.5 && \
1739 echo g && sleep 0.5 && echo h"
1740 https://github.com/amattn/paral (Last checked: 2019-01)
1742 DIFFERENCES BETWEEN concurr AND GNU Parallel
1744 concurr is built to run jobs in parallel using a client/server model.
1745 EXAMPLES FROM README.md
1747 The examples from README.md:
1749 1$ concurr 'echo job {#} on slot {%}: {}' : arg1 arg2 arg3 arg4
1751 1$ parallel 'echo job {#} on slot {%}: {}' ::: arg1 arg2 arg3 arg4
1752 2$ concurr 'echo job {#} on slot {%}: {}' :: file1 file2 file3
1754 2$ parallel 'echo job {#} on slot {%}: {}' :::: file1 file2 file3
1755 3$ concurr 'echo {}' < input_file
1757 3$ parallel 'echo {}' < input_file
1758 4$ cat file | concurr 'echo {}'
1760 4$ cat file | parallel 'echo {}'
1761 concurr deals badly empty input files and with output larger than 64
1763 KB.
1764 https://github.com/mmstick/concurr (Last checked: 2019-01)
1766 DIFFERENCES BETWEEN lesser-parallel AND GNU Parallel
1768 lesser-parallel is the inspiration for parallel --embed. Both lesser-
1769 parallel and parallel --embed define bash functions that can be
1770 included as part of a bash script to run jobs in parallel.
1771 lesser-parallel implements a few of the replacement strings, but hardly
1773 any options, whereas parallel --embed gives you the full GNU parallel
1774 experience.
1775 https://github.com/kou1okada/lesser-parallel (Last checked: 2019-01)
1777 DIFFERENCES BETWEEN npm-parallel AND GNU Parallel
1779 npm-parallel can run npm tasks in parallel.
1780 There are no examples and very little documentation, so it is hard to
1782 compare to GNU parallel.
1783 https://github.com/spion/npm-parallel (Last checked: 2019-01)
1785 DIFFERENCES BETWEEN machma AND GNU Parallel
1787 machma runs tasks in parallel. It gives time stamped output. It buffers
1788 in RAM.
1789 EXAMPLES FROM README.md
1791 The examples from README.md:
1793 1$ # Put shorthand for timestamp in config for the examples
1795 echo '--rpl '\
1796 \''{time} $_=::strftime("%Y-%m-%d %H:%M:%S",localtime())'\' \
1797 > ~/.parallel/machma
1798 echo '--line-buffer --tagstring "{#} {time} {}"' \
1799 >> ~/.parallel/machma
1800 2$ find . -iname '*.jpg' |
1802 machma -- mogrify -resize 1200x1200 -filter Lanczos {}
1803 find . -iname '*.jpg' |
1804 parallel --bar -Jmachma mogrify -resize 1200x1200 \
1805 -filter Lanczos {}
1806 3$ cat /tmp/ips | machma -p 2 -- ping -c 2 -q {}
1808 3$ cat /tmp/ips | parallel -j2 -Jmachma ping -c 2 -q {}
1809 4$ cat /tmp/ips |
1811 machma -- sh -c 'ping -c 2 -q $0 > /dev/null && echo alive' {}
1812 4$ cat /tmp/ips |
1813 parallel -Jmachma 'ping -c 2 -q {} > /dev/null && echo alive'
1814 5$ find . -iname '*.jpg' |
1816 machma --timeout 5s -- mogrify -resize 1200x1200 \
1817 -filter Lanczos {}
1818 5$ find . -iname '*.jpg' |
1819 parallel --timeout 5s --bar mogrify -resize 1200x1200 \
1820 -filter Lanczos {}
1821 6$ find . -iname '*.jpg' -print0 |
1823 machma --null -- mogrify -resize 1200x1200 -filter Lanczos {}
1824 6$ find . -iname '*.jpg' -print0 |
1825 parallel --null --bar mogrify -resize 1200x1200 \
1826 -filter Lanczos {}
1827 https://github.com/fd0/machma (Last checked: 2019-06)
1829 DIFFERENCES BETWEEN interlace AND GNU Parallel
1831 Summary table (see legend above): - I2 I3 I4 - - - M1 - M3 - - M6 - O2
1832 O3 - - - - x x E1 E2 - - - - - - - - - - - - - - - -
1833 interlace is built for network analysis to run network tools in
1835 parallel.
1836 interface does not buffer output, so output from different jobs mixes.
1838 The overhead for each target is O(n*n), so with 1000 targets it becomes
1840 very slow with an overhead in the order of 500ms/target.
1841 EXAMPLES FROM interlace's WEBSITE
1843 Using prips most of the examples from
1845 https://github.com/codingo/Interlace can be run with GNU parallel:
1846 Blocker
1848 commands.txt:
1850 mkdir -p _output_/_target_/scans/
1851 _blocker_
1852 nmap _target_ -oA _output_/_target_/scans/_target_-nmap
1853 interlace -tL ./targets.txt -cL commands.txt -o $output
1854 parallel -a targets.txt \
1856 mkdir -p $output/{}/scans/\; nmap {} -oA $output/{}/scans/{}-nmap
1857 Blocks
1859 commands.txt:
1861 _block:nmap_
1862 mkdir -p _target_/output/scans/
1863 nmap _target_ -oN _target_/output/scans/_target_-nmap
1864 _block:nmap_
1865 nikto --host _target_
1866 interlace -tL ./targets.txt -cL commands.txt
1867 _nmap() {
1869 mkdir -p $1/output/scans/
1870 nmap $1 -oN $1/output/scans/$1-nmap
1871 }
1872 export -f _nmap
1873 parallel ::: _nmap "nikto --host" :::: targets.txt
1874 Run Nikto Over Multiple Sites
1876 interlace -tL ./targets.txt -threads 5 \
1878 -c "nikto --host _target_ > ./_target_-nikto.txt" -v
1879 parallel -a targets.txt -P5 nikto --host {} \> ./{}_-nikto.txt
1881 Run Nikto Over Multiple Sites and Ports
1883 interlace -tL ./targets.txt -threads 5 -c \
1885 "nikto --host _target_:_port_ > ./_target_-_port_-nikto.txt" \
1886 -p 80,443 -v
1887 parallel -P5 nikto --host {1}:{2} \> ./{1}-{2}-nikto.txt \
1889 :::: targets.txt ::: 80 443
1890 Run a List of Commands against Target Hosts
1892 commands.txt:
1894 nikto --host _target_:_port_ > _output_/_target_-nikto.txt
1895 sslscan _target_:_port_ > _output_/_target_-sslscan.txt
1896 testssl.sh _target_:_port_ > _output_/_target_-testssl.txt
1897 interlace -t example.com -o ~/Engagements/example/ \
1898 -cL ./commands.txt -p 80,443
1899 parallel --results ~/Engagements/example/{2}:{3}{1} {1} {2}:{3} \
1901 ::: "nikto --host" sslscan testssl.sh ::: example.com ::: 80 443
1902 CIDR notation with an application that doesn't support it
1904 interlace -t 192.168.12.0/24 -c "vhostscan _target_ \
1906 -oN _output_/_target_-vhosts.txt" -o ~/scans/ -threads 50
1907 prips 192.168.12.0/24 |
1909 parallel -P50 vhostscan {} -oN ~/scans/{}-vhosts.txt
1910 Glob notation with an application that doesn't support it
1912 interlace -t 192.168.12.* -c "vhostscan _target_ \
1914 -oN _output_/_target_-vhosts.txt" -o ~/scans/ -threads 50
1915 # Glob is not supported in prips
1917 prips 192.168.12.0/24 |
1918 parallel -P50 vhostscan {} -oN ~/scans/{}-vhosts.txt
1919 Dash (-) notation with an application that doesn't support it
1921 interlace -t 192.168.12.1-15 -c \
1923 "vhostscan _target_ -oN _output_/_target_-vhosts.txt" \
1924 -o ~/scans/ -threads 50
1925 # Dash notation is not supported in prips
1927 prips 192.168.12.1 192.168.12.15 |
1928 parallel -P50 vhostscan {} -oN ~/scans/{}-vhosts.txt
1929 Threading Support for an application that doesn't support it
1931 interlace -tL ./target-list.txt -c \
1933 "vhostscan -t _target_ -oN _output_/_target_-vhosts.txt" \
1934 -o ~/scans/ -threads 50
1935 cat ./target-list.txt |
1937 parallel -P50 vhostscan -t {} -oN ~/scans/{}-vhosts.txt
1938 alternatively
1940 ./vhosts-commands.txt:
1942 vhostscan -t $target -oN _output_/_target_-vhosts.txt
1943 interlace -cL ./vhosts-commands.txt -tL ./target-list.txt \
1944 -threads 50 -o ~/scans
1945 ./vhosts-commands.txt:
1947 vhostscan -t "$1" -oN "$2"
1948 parallel -P50 ./vhosts-commands.txt {} ~/scans/{}-vhosts.txt \
1949 :::: ./target-list.txt
1950 Exclusions
1952 interlace -t 192.168.12.0/24 -e 192.168.12.0/26 -c \
1954 "vhostscan _target_ -oN _output_/_target_-vhosts.txt" \
1955 -o ~/scans/ -threads 50
1956 prips 192.168.12.0/24 | grep -xv -Ff <(prips 192.168.12.0/26) |
1958 parallel -P50 vhostscan {} -oN ~/scans/{}-vhosts.txt
1959 Run Nikto Using Multiple Proxies
1961 interlace -tL ./targets.txt -pL ./proxies.txt -threads 5 -c \
1963 "nikto --host _target_:_port_ -useproxy _proxy_ > \
1964 ./_target_-_port_-nikto.txt" -p 80,443 -v
1965 parallel -j5 \
1967 "nikto --host {1}:{2} -useproxy {3} > ./{1}-{2}-nikto.txt" \
1968 :::: ./targets.txt ::: 80 443 :::: ./proxies.txt
1969 https://github.com/codingo/Interlace (Last checked: 2019-09)
1971 DIFFERENCES BETWEEN otonvm Parallel AND GNU Parallel
1973 I have been unable to get the code to run at all. It seems unfinished.
1974 https://github.com/otonvm/Parallel (Last checked: 2019-02)
1976 DIFFERENCES BETWEEN k-bx par AND GNU Parallel
1978 par requires Haskell to work. This limits the number of platforms this
1979 can work on.
1980 par does line buffering in memory. The memory usage is 3x the longest
1982 line (compared to 1x for parallel --lb). Commands must be given as
1983 arguments. There is no template.
1984 These are the examples from https://github.com/k-bx/par with the
1986 corresponding GNU parallel command.
1987 par "echo foo; sleep 1; echo foo; sleep 1; echo foo" \
1989 "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
1990 parallel --lb ::: "echo foo; sleep 1; echo foo; sleep 1; echo foo" \
1991 "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
1992 par "echo foo; sleep 1; foofoo" \
1994 "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
1995 parallel --lb --halt 1 ::: "echo foo; sleep 1; foofoo" \
1996 "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
1997 par "PARPREFIX=[fooechoer] echo foo" "PARPREFIX=[bar] echo bar"
1999 parallel --lb --colsep , --tagstring {1} {2} \
2000 ::: "[fooechoer],echo foo" "[bar],echo bar"
2001 par --succeed "foo" "bar" && echo 'wow'
2003 parallel "foo" "bar"; true && echo 'wow'
2004 https://github.com/k-bx/par (Last checked: 2019-02)
2006 DIFFERENCES BETWEEN parallelshell AND GNU Parallel
2008 parallelshell does not allow for composed commands:
2009 # This does not work
2011 parallelshell 'echo foo;echo bar' 'echo baz;echo quuz'
2012 Instead you have to wrap that in a shell:
2014 parallelshell 'sh -c "echo foo;echo bar"' 'sh -c "echo baz;echo quuz"'
2016 It buffers output in RAM. All commands must be given on the command
2018 line and all commands are started in parallel at the same time. This
2019 will cause the system to freeze if there are so many jobs that there is
2020 not enough memory to run them all at the same time.
2021 https://github.com/keithamus/parallelshell (Last checked: 2019-02)
2023 https://github.com/darkguy2008/parallelshell (Last checked: 2019-03)
2025 DIFFERENCES BETWEEN shell-executor AND GNU Parallel
2027 shell-executor does not allow for composed commands:
2028 # This does not work
2030 sx 'echo foo;echo bar' 'echo baz;echo quuz'
2031 Instead you have to wrap that in a shell:
2033 sx 'sh -c "echo foo;echo bar"' 'sh -c "echo baz;echo quuz"'
2035 It buffers output in RAM. All commands must be given on the command
2037 line and all commands are started in parallel at the same time. This
2038 will cause the system to freeze if there are so many jobs that there is
2039 not enough memory to run them all at the same time.
2040 https://github.com/royriojas/shell-executor (Last checked: 2019-02)
2042 DIFFERENCES BETWEEN non-GNU par AND GNU Parallel
2044 par buffers in memory to avoid mixing of jobs. It takes 1s per 1
2045 million output lines.
2046 par needs to have all commands before starting the first job. The jobs
2048 are read from stdin (standard input) so any quoting will have to be
2049 done by the user.
2050 Stdout (standard output) is prepended with o:. Stderr (standard error)
2052 is sendt to stdout (standard output) and prepended with e:.
2053 For short jobs with little output par is 20% faster than GNU parallel
2055 and 60% slower than xargs.
2056 http://savannah.nongnu.org/projects/par (Last checked: 2019-02)
2058 DIFFERENCES BETWEEN fd AND GNU Parallel
2060 fd does not support composed commands, so commands must be wrapped in
2061 sh -c.
2062 It buffers output in RAM.
2064 It only takes file names from the filesystem as input (similar to
2066 find).
2067 https://github.com/sharkdp/fd (Last checked: 2019-02)
2069 DIFFERENCES BETWEEN lateral AND GNU Parallel
2071 lateral is very similar to sem: It takes a single command and runs it
2072 in the background. The design means that output from parallel running
2073 jobs may mix. If it dies unexpectly it leaves a socket in
2074 ~/.lateral/socket.PID.
2075 lateral deals badly with too long command lines. This makes the lateral
2077 server crash:
2078 lateral run echo `seq 100000| head -c 1000k`
2080 Any options will be read by lateral so this does not work (lateral
2082 interprets the -l):
2083 lateral run ls -l
2085 Composed commands do not work:
2087 lateral run pwd ';' ls
2089 Functions do not work:
2091 myfunc() { echo a; }
2093 export -f myfunc
2094 lateral run myfunc
2095 Running emacs in the terminal causes the parent shell to die:
2097 echo '#!/bin/bash' > mycmd
2099 echo emacs -nw >> mycmd
2100 chmod +x mycmd
2101 lateral start
2102 lateral run ./mycmd
2103 Here are the examples from https://github.com/akramer/lateral with the
2105 corresponding GNU sem and GNU parallel commands:
2106 1$ lateral start
2108 1$ for i in $(cat /tmp/names); do
2109 1$ lateral run -- some_command $i
2110 1$ done
2111 1$ lateral wait
2112 1$
2113 1$ for i in $(cat /tmp/names); do
2114 1$ sem some_command $i
2115 1$ done
2116 1$ sem --wait
2117 1$
2118 1$ parallel some_command :::: /tmp/names
2119 2$ lateral start
2121 2$ for i in $(seq 1 100); do
2122 2$ lateral run -- my_slow_command < workfile$i > /tmp/logfile$i
2123 2$ done
2124 2$ lateral wait
2125 2$
2126 2$ for i in $(seq 1 100); do
2127 2$ sem my_slow_command < workfile$i > /tmp/logfile$i
2128 2$ done
2129 2$ sem --wait
2130 2$
2131 2$ parallel 'my_slow_command < workfile{} > /tmp/logfile{}' \
2132 ::: {1..100}
2133 3$ lateral start -p 0 # yup, it will just queue tasks
2135 3$ for i in $(seq 1 100); do
2136 3$ lateral run -- command_still_outputs_but_wont_spam inputfile$i
2137 3$ done
2138 3$ # command output spam can commence
2139 3$ lateral config -p 10; lateral wait
2140 3$
2141 3$ for i in $(seq 1 100); do
2142 3$ echo "command inputfile$i" >> joblist
2143 3$ done
2144 3$ parallel -j 10 :::: joblist
2145 3$
2146 3$ echo 1 > /tmp/njobs
2147 3$ parallel -j /tmp/njobs command inputfile{} \
2148 ::: {1..100} &
2149 3$ echo 10 >/tmp/njobs
2150 3$ wait
2151 https://github.com/akramer/lateral (Last checked: 2019-03)
2153 DIFFERENCES BETWEEN with-this AND GNU Parallel
2155 The examples from https://github.com/amritb/with-this.git and the
2156 corresponding GNU parallel command:
2157 with -v "$(cat myurls.txt)" "curl -L this"
2159 parallel curl -L ::: myurls.txt
2160 with -v "$(cat myregions.txt)" \
2162 "aws --region=this ec2 describe-instance-status"
2163 parallel aws --region={} ec2 describe-instance-status \
2164 :::: myregions.txt
2165 with -v "$(ls)" "kubectl --kubeconfig=this get pods"
2167 ls | parallel kubectl --kubeconfig={} get pods
2168 with -v "$(ls | grep config)" "kubectl --kubeconfig=this get pods"
2170 ls | grep config | parallel kubectl --kubeconfig={} get pods
2171 with -v "$(echo {1..10})" "echo 123"
2173 parallel -N0 echo 123 ::: {1..10}
2174 Stderr is merged with stdout. with-this buffers in RAM. It uses 3x the
2176 output size, so you cannot have output larger than 1/3rd the amount of
2177 RAM. The input values cannot contain spaces. Composed commands do not
2178 work.
2179 with-this gives some additional information, so the output has to be
2181 cleaned before piping it to the next command.
2182 https://github.com/amritb/with-this.git (Last checked: 2019-03)
2184 DIFFERENCES BETWEEN Tollef's parallel (moreutils) AND GNU Parallel
2186 Summary table (see legend above): - - - I4 - - I7 - - M3 - - M6 - O2 O3
2187 - O5 O6 - x x E1 - - - - - E7 - x x x x x x x x - -
2188 EXAMPLES FROM Tollef's parallel MANUAL
2190 Tollef parallel sh -c "echo hi; sleep 2; echo bye" -- 1 2 3
2192 GNU parallel "echo hi; sleep 2; echo bye" ::: 1 2 3
2194 Tollef parallel -j 3 ufraw -o processed -- *.NEF
2196 GNU parallel -j 3 ufraw -o processed ::: *.NEF
2198 Tollef parallel -j 3 -- ls df "echo hi"
2200 GNU parallel -j 3 ::: ls df "echo hi"
2202 (Last checked: 2019-08)
2204 DIFFERENCES BETWEEN rargs AND GNU Parallel
2206 Summary table (see legend above): I1 - - - - - I7 - - M3 M4 - - - O2 O3
2207 - O5 O6 - O8 - E1 - - E4 - - - - - - - - - - - - - -
2208 rargs has elegant ways of doing named regexp capture and field ranges.
2210 With GNU parallel you can use --rpl to get a similar functionality as
2212 regexp capture gives, and use join and @arg to get the field ranges.
2213 But the syntax is longer. This:
2214 --rpl '{r(\d+)\.\.(\d+)} $_=join"$opt::colsep",@arg[$$1..$$2]'
2216 would make it possible to use:
2218 {1r3..6}
2220 for field 3..6.
2222 For full support of {n..m:s} including negative numbers use a dynamic
2224 replacement string like this:
2225 PARALLEL=--rpl\ \''{r((-?\d+)?)\.\.((-?\d+)?)((:([^}]*))?)}
2227 $a = defined $$2 ? $$2 < 0 ? 1+$#arg+$$2 : $$2 : 1;
2228 $b = defined $$4 ? $$4 < 0 ? 1+$#arg+$$4 : $$4 : $#arg+1;
2229 $s = defined $$6 ? $$7 : " ";
2230 $_ = join $s,@arg[$a..$b]'\'
2231 export PARALLEL
2232 You can then do:
2234 head /etc/passwd | parallel --colsep : echo ..={1r..} ..3={1r..3} \
2236 4..={1r4..} 2..4={1r2..4} 3..3={1r3..3} ..3:-={1r..3:-} \
2237 ..3:/={1r..3:/} -1={-1} -5={-5} -6={-6} -3..={1r-3..}
2238 EXAMPLES FROM rargs MANUAL
2240 ls *.bak | rargs -p '(.*)\.bak' mv {0} {1}
2242 ls *.bak | parallel mv {} {.}
2243 cat download-list.csv | rargs -p '(?P<url>.*),(?P<filename>.*)' wget {url} -O {filename}
2245 cat download-list.csv | parallel --csv wget {1} -O {2}
2246 # or use regexps:
2247 cat download-list.csv |
2248 parallel --rpl '{url} s/,.*//' --rpl '{filename} s/.*?,//' wget {url} -O {filename}
2249 cat /etc/passwd | rargs -d: echo -e 'id: "{1}"\t name: "{5}"\t rest: "{6..::}"'
2251 cat /etc/passwd |
2252 parallel -q --colsep : echo -e 'id: "{1}"\t name: "{5}"\t rest: "{=6 $_=join":",@arg[6..$#arg]=}"'
2253 https://github.com/lotabout/rargs (Last checked: 2020-01)
2255 DIFFERENCES BETWEEN threader AND GNU Parallel
2257 Summary table (see legend above): I1 - - - - - - M1 - M3 - - M6 O1 - O3
2258 - O5 - - N/A N/A E1 - - E4 - - - - - - - - - - - - - -
2259 Newline separates arguments, but newline at the end of file is treated
2261 as an empty argument. So this runs 2 jobs:
2262 echo two_jobs | threader -run 'echo "$THREADID"'
2264 threader ignores stderr, so any output to stderr is lost. threader
2266 buffers in RAM, so output bigger than the machine's virtual memory will
2267 cause the machine to crash.
2268 https://github.com/voodooEntity/threader (Last checked: 2020-04)
2270 DIFFERENCES BETWEEN runp AND GNU Parallel
2272 Summary table (see legend above): I1 I2 - - - - - M1 - (M3) - - M6 O1
2273 O2 O3 - O5 O6 - N/A N/A - E1 - - - - - - - - - - - - - - - - -
2274 (M3): You can add a prefix and a postfix to the input, so it means you
2276 can only insert the argument on the command line once.
2277 runp runs 10 jobs in parallel by default. runp blocks if output of a
2279 command is > 64 Kbytes. Quoting of input is needed. It adds output to
2280 stderr (this can be prevented with -q)
2281 Examples as GNU Parallel
2283 base='https://images-api.nasa.gov/search'
2285 query='jupiter'
2286 desc='planet'
2287 type='image'
2288 url="$base?q=$query&description=$desc&media_type=$type"
2289 # Download the images in parallel using runp
2291 curl -s $url | jq -r .collection.items[].href | \
2292 runp -p 'curl -s' | jq -r .[] | grep large | \
2293 runp -p 'curl -s -L -O'
2294 time curl -s $url | jq -r .collection.items[].href | \
2296 runp -g 1 -q -p 'curl -s' | jq -r .[] | grep large | \
2297 runp -g 1 -q -p 'curl -s -L -O'
2298 # Download the images in parallel
2300 curl -s $url | jq -r .collection.items[].href | \
2301 parallel curl -s | jq -r .[] | grep large | \
2302 parallel curl -s -L -O
2303 time curl -s $url | jq -r .collection.items[].href | \
2305 parallel -j 1 curl -s | jq -r .[] | grep large | \
2306 parallel -j 1 curl -s -L -O
2307 Run some test commands (read from file)
2309 # Create a file containing commands to run in parallel.
2311 cat << EOF > /tmp/test-commands.txt
2312 sleep 5
2313 sleep 3
2314 blah # this will fail
2315 ls $PWD # PWD shell variable is used here
2316 EOF
2317 # Run commands from the file.
2319 runp /tmp/test-commands.txt > /dev/null
2320 parallel -a /tmp/test-commands.txt > /dev/null
2322 Ping several hosts and see packet loss (read from stdin)
2324 # First copy this line and press Enter
2326 runp -p 'ping -c 5 -W 2' -s '| grep loss'
2327 localhost
2328 1.1.1.1
2329 8.8.8.8
2330 # Press Enter and Ctrl-D when done entering the hosts
2331 # First copy this line and press Enter
2333 parallel ping -c 5 -W 2 {} '| grep loss'
2334 localhost
2335 1.1.1.1
2336 8.8.8.8
2337 # Press Enter and Ctrl-D when done entering the hosts
2338 Get directories' sizes (read from stdin)
2340 echo -e "$HOME\n/etc\n/tmp" | runp -q -p 'sudo du -sh'
2342 echo -e "$HOME\n/etc\n/tmp" | parallel sudo du -sh
2344 # or:
2345 parallel sudo du -sh ::: "$HOME" /etc /tmp
2346 Compress files
2348 find . -iname '*.txt' | runp -p 'gzip --best'
2350 find . -iname '*.txt' | parallel gzip --best
2352 Measure HTTP request + response time
2354 export CURL="curl -w 'time_total: %{time_total}\n'"
2356 CURL="$CURL -o /dev/null -s https://golang.org/"
2357 perl -wE 'for (1..10) { say $ENV{CURL} }' |
2358 runp -q # Make 10 requests
2359 perl -wE 'for (1..10) { say $ENV{CURL} }' | parallel
2361 # or:
2362 parallel -N0 "$CURL" ::: {1..10}
2363 Find open TCP ports
2365 cat << EOF > /tmp/host-port.txt
2367 localhost 22
2368 localhost 80
2369 localhost 81
2370 127.0.0.1 443
2371 127.0.0.1 444
2372 scanme.nmap.org 22
2373 scanme.nmap.org 23
2374 scanme.nmap.org 443
2375 EOF
2376 cat /tmp/host-port.txt | \
2378 runp -q -p 'netcat -v -w2 -z' 2>&1 | egrep '(succeeded!|open)$'
2379 # --colsep is needed to split the line
2381 cat /tmp/host-port.txt | \
2382 parallel --colsep ' ' netcat -v -w2 -z 2>&1 | egrep '(succeeded!|open)$'
2383 # or use uq for unquoted:
2384 cat /tmp/host-port.txt | \
2385 parallel netcat -v -w2 -z {=uq=} 2>&1 | egrep '(succeeded!|open)$'
2386 https://github.com/jreisinger/runp (Last checked: 2020-04)
2388 DIFFERENCES BETWEEN papply AND GNU Parallel
2390 Summary table (see legend above): - - - I4 - - - M1 - M3 - - M6 - - O3
2391 - O5 - - N/A N/A O10 E1 - - E4 - - - - - - - - - - - - - -
2392 papply does not print the output if the command fails:
2394 $ papply 'echo %F; false' foo
2396 "echo foo; false" did not succeed
2397 papply's replacement strings (%F %d %f %n %e %z) can be simulated in
2399 GNU parallel by putting this in ~/.parallel/config:
2400 --rpl '%F'
2402 --rpl '%d $_=Q(::dirname($_));'
2403 --rpl '%f s:.*/::;'
2404 --rpl '%n s:.*/::;s:\.[^/.]+$::;'
2405 --rpl '%e s:.*\.:.:'
2406 --rpl '%z $_=""'
2407 papply buffers in RAM, and uses twice the amount of output. So output
2409 of 5 GB takes 10 GB RAM.
2410 The buffering is very CPU intensive: Buffering a line of 5 GB takes 40
2412 seconds (compared to 10 seconds with GNU parallel).
2413 Examples as GNU Parallel
2415 1$ papply gzip *.txt
2417 1$ parallel gzip ::: *.txt
2419 2$ papply "convert %F %n.jpg" *.png
2421 2$ parallel convert {} {.}.jpg ::: *.png
2423 https://pypi.org/project/papply/ (Last checked: 2020-04)
2425 Todo
2427 https://gitlab.com/netikras/bthread
2428 https://github.com/JeiKeiLim/simple_distribute_job
2430 https://github.com/reggi/pkgrun
2432 https://github.com/benoror/better-npm-run - not obvious how to use
2434 https://github.com/bahmutov/with-package
2436 https://github.com/xuchenCN/go-pssh
2438 https://github.com/flesler/parallel
2440 https://github.com/Julian/Verge
2442 https://github.com/ExpectationMax/simple_gpu_scheduler
2444 simple_gpu_scheduler --gpus 0 1 2 < gpu_commands.txt
2445 parallel -j3 --shuf CUDA_VISIBLE_DEVICES='{=1 $_=slot()-1 =}
2446 {=uq;=}' < gpu_commands.txt
2447 simple_hypersearch "python3 train_dnn.py --lr {lr} --batch_size {bs}" -p lr 0.001 0.0005 0.0001 -p bs 32 64 128 | simple_gpu_scheduler --gpus 0,1,2
2449 parallel --header : --shuf -j3 -v CUDA_VISIBLE_DEVICES='{=1 $_=slot()-1 =}' python3 train_dnn.py --lr {lr} --batch_size {bs} ::: lr 0.001 0.0005 0.0001 ::: bs 32 64 128
2450 simple_hypersearch "python3 train_dnn.py --lr {lr} --batch_size {bs}" --n-samples 5 -p lr 0.001 0.0005 0.0001 -p bs 32 64 128 | simple_gpu_scheduler --gpus 0,1,2
2452 parallel --header : --shuf CUDA_VISIBLE_DEVICES='{=1 $_=slot()-1; seq() > 5 and skip() =}' python3 train_dnn.py --lr {lr} --batch_size {bs} ::: lr 0.001 0.0005 0.0001 ::: bs 32 64 128
2453 touch gpu.queue
2455 tail -f -n 0 gpu.queue | simple_gpu_scheduler --gpus 0,1,2 &
2456 echo "my_command_with | and stuff > logfile" >> gpu.queue
2457 touch gpu.queue
2459 tail -f -n 0 gpu.queue | parallel -j3 CUDA_VISIBLE_DEVICES='{=1 $_=slot()-1 =} {=uq;=}' &
2460 # Needed to fill job slots once
2461 seq 3 | parallel echo true >> gpu.queue
2462 # Add jobs
2463 echo "my_command_with | and stuff > logfile" >> gpu.queue
2464 # Needed to flush output from completed jobs
2465 seq 3 | parallel echo true >> gpu.queue
2466
2468 There are certain issues that are very common on parallelizing tools.
2469 Here are a few stress tests. Be warned: If the tool is badly coded it
2470 may overload your machine.
2471 MIX: Output mixes
2473 Output from 2 jobs should not mix. If the output is not used, this does
2474 not matter; but if the output is used then it is important that you do
2475 not get half a line from one job followed by half a line from another
2476 job.
2477 If the tool does not buffer, output will most likely mix now and then.
2479 This test stresses whether output mixes.
2481 #!/bin/bash
2483 paralleltool="parallel -j0"
2485 cat <<-EOF > mycommand
2487 #!/bin/bash
2488 # If a, b, c, d, e, and f mix: Very bad
2490 perl -e 'print STDOUT "a"x3000_000," "'
2491 perl -e 'print STDERR "b"x3000_000," "'
2492 perl -e 'print STDOUT "c"x3000_000," "'
2493 perl -e 'print STDERR "d"x3000_000," "'
2494 perl -e 'print STDOUT "e"x3000_000," "'
2495 perl -e 'print STDERR "f"x3000_000," "'
2496 echo
2497 echo >&2
2498 EOF
2499 chmod +x mycommand
2500 # Run 30 jobs in parallel
2502 seq 30 |
2503 $paralleltool ./mycommand > >(tr -s abcdef) 2> >(tr -s abcdef >&2)
2504 # 'a c e' and 'b d f' should always stay together
2506 # and there should only be a single line per job
2507 STDERRMERGE: Stderr is merged with stdout
2509 Output from stdout and stderr should not be merged, but kept separated.
2510 This test shows whether stdout is mixed with stderr.
2512 #!/bin/bash
2514 paralleltool="parallel -j0"
2516 cat <<-EOF > mycommand
2518 #!/bin/bash
2519 echo stdout
2521 echo stderr >&2
2522 echo stdout
2523 echo stderr >&2
2524 EOF
2525 chmod +x mycommand
2526 # Run one job
2528 echo |
2529 $paralleltool ./mycommand > stdout 2> stderr
2530 cat stdout
2531 cat stderr
2532 RAM: Output limited by RAM
2534 Some tools cache output in RAM. This makes them extremely slow if the
2535 output is bigger than physical memory and crash if the output is bigger
2536 than the virtual memory.
2537 #!/bin/bash
2539 paralleltool="parallel -j0"
2541 cat <<'EOF' > mycommand
2543 #!/bin/bash
2544 # Generate 1 GB output
2546 yes "`perl -e 'print \"c\"x30_000'`" | head -c 1G
2547 EOF
2548 chmod +x mycommand
2549 # Run 20 jobs in parallel
2551 # Adjust 20 to be > physical RAM and < free space on /tmp
2552 seq 20 | time $paralleltool ./mycommand | wc -c
2553 DISKFULL: Incomplete data if /tmp runs full
2555 If caching is done on disk, the disk can run full during the run. Not
2556 all programs discover this. GNU Parallel discovers it, if it stays full
2557 for at least 2 seconds.
2558 #!/bin/bash
2560 paralleltool="parallel -j0"
2562 # This should be a dir with less than 100 GB free space
2564 smalldisk=/tmp/shm/parallel
2565 TMPDIR="$smalldisk"
2567 export TMPDIR
2568 max_output() {
2570 # Force worst case scenario:
2571 # Make GNU Parallel only check once per second
2572 sleep 10
2573 # Generate 100 GB to fill $TMPDIR
2574 # Adjust if /tmp is bigger than 100 GB
2575 yes | head -c 100G >$TMPDIR/$$
2576 # Generate 10 MB output that will not be buffered due to full disk
2577 perl -e 'print "X"x10_000_000' | head -c 10M
2578 echo This part is missing from incomplete output
2579 sleep 2
2580 rm $TMPDIR/$$
2581 echo Final output
2582 }
2583 export -f max_output
2585 seq 10 | $paralleltool max_output | tr -s X
2586 CLEANUP: Leaving tmp files at unexpected death
2588 Some tools do not clean up tmp files if they are killed. If the tool
2589 buffers on disk, they may not clean up, if they are killed.
2590 #!/bin/bash
2592 paralleltool=parallel
2594 ls /tmp >/tmp/before
2596 seq 10 | $paralleltool sleep &
2597 pid=$!
2598 # Give the tool time to start up
2599 sleep 1
2600 # Kill it without giving it a chance to cleanup
2601 kill -9 $!
2602 # Should be empty: No files should be left behind
2603 diff <(ls /tmp) /tmp/before
2604 SPCCHAR: Dealing badly with special file names.
2606 It is not uncommon for users to create files like:
2607 My brother's 12" *** record (costs $$$).jpg
2609 Some tools break on this.
2611 #!/bin/bash
2613 paralleltool=parallel
2615 touch "My brother's 12\" *** record (costs \$\$\$).jpg"
2617 ls My*jpg | $paralleltool ls -l
2618 COMPOSED: Composed commands do not work
2620 Some tools require you to wrap composed commands into bash -c.
2621 echo bar | $paralleltool echo foo';' echo {}
2623 ONEREP: Only one replacement string allowed
2625 Some tools can only insert the argument once.
2626 echo bar | $paralleltool echo {} foo {}
2628 INPUTSIZE: Length of input should not be limited
2630 Some tools limit the length of the input lines artificially with no
2631 good reason. GNU parallel does not:
2632 perl -e 'print "foo."."x"x100_000_000' | parallel echo {.}
2634 GNU parallel limits the command to run to 128 KB due to execve(1):
2636 perl -e 'print "x"x131_000' | parallel echo {} | wc
2638 NUMWORDS: Speed depends on number of words
2640 Some tools become very slow if output lines have many words.
2641 #!/bin/bash
2643 paralleltool=parallel
2645 cat <<-EOF > mycommand
2647 #!/bin/bash
2648 # 10 MB of lines with 1000 words
2650 yes "`seq 1000`" | head -c 10M
2651 EOF
2652 chmod +x mycommand
2653 # Run 30 jobs in parallel
2655 seq 30 | time $paralleltool -j0 ./mycommand > /dev/null
2656 4GB: Output with a line > 4GB should be OK
2658 #!/bin/bash
2659 paralleltool="parallel -j0"
2661 cat <<-EOF > mycommand
2663 #!/bin/bash
2664 perl -e '\$a="a"x1000_000; for(1..5000) { print \$a }'
2666 EOF
2667 chmod +x mycommand
2668 # Run 1 job
2670 seq 1 | $paralleltool ./mycommand | LC_ALL=C wc
2671
2673 When using GNU parallel for a publication please cite:
2674 O. Tange (2011): GNU Parallel - The Command-Line Power Tool, ;login:
2676 The USENIX Magazine, February 2011:42-47.
2677 This helps funding further development; and it won't cost you a cent.
2679 If you pay 10000 EUR you should feel free to use GNU Parallel without
2680 citing.
2681 Copyright (C) 2007-10-18 Ole Tange, http://ole.tange.dk
2683 Copyright (C) 2008-2010 Ole Tange, http://ole.tange.dk
2685 Copyright (C) 2010-2020 Ole Tange, http://ole.tange.dk and Free
2687 Software Foundation, Inc.
2688 Parts of the manual concerning xargs compatibility is inspired by the
2690 manual of xargs from GNU findutils 4.4.2.
2691
2693 This program is free software; you can redistribute it and/or modify it
2694 under the terms of the GNU General Public License as published by the
2695 Free Software Foundation; either version 3 of the License, or at your
2696 option any later version.
2697 This program is distributed in the hope that it will be useful, but
2699 WITHOUT ANY WARRANTY; without even the implied warranty of
2700 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
2701 General Public License for more details.
2702 You should have received a copy of the GNU General Public License along
2704 with this program. If not, see <http://www.gnu.org/licenses/>.
2705 Documentation license I
2707 Permission is granted to copy, distribute and/or modify this
2708 documentation under the terms of the GNU Free Documentation License,
2709 Version 1.3 or any later version published by the Free Software
2710 Foundation; with no Invariant Sections, with no Front-Cover Texts, and
2711 with no Back-Cover Texts. A copy of the license is included in the
2712 file fdl.txt.
2713 Documentation license II
2715 You are free:
2716 to Share to copy, distribute and transmit the work
2718 to Remix to adapt the work
2720 Under the following conditions:
2722 Attribution
2724 You must attribute the work in the manner specified by the
2725 author or licensor (but not in any way that suggests that they
2726 endorse you or your use of the work).
2727 Share Alike
2729 If you alter, transform, or build upon this work, you may
2730 distribute the resulting work only under the same, similar or
2731 a compatible license.
2732 With the understanding that:
2734 Waiver Any of the above conditions can be waived if you get
2736 permission from the copyright holder.
2737 Public Domain
2739 Where the work or any of its elements is in the public domain
2740 under applicable law, that status is in no way affected by the
2741 license.
2742 Other Rights
2744 In no way are any of the following rights affected by the
2745 license:
2746 · Your fair dealing or fair use rights, or other applicable
2748 copyright exceptions and limitations;
2749 · The author's moral rights;
2751 · Rights other persons may have either in the work itself or
2753 in how the work is used, such as publicity or privacy
2754 rights.
2755 Notice For any reuse or distribution, you must make clear to others
2757 the license terms of this work.
2758 A copy of the full license is included in the file as cc-by-sa.txt.
2760
2762 GNU parallel uses Perl, and the Perl modules Getopt::Long, IPC::Open3,
2763 Symbol, IO::File, POSIX, and File::Temp. For remote usage it also uses
2764 rsync with ssh.
2765
2767 find(1), xargs(1), make(1), pexec(1), ppss(1), xjobs(1), prll(1),
2768 dxargs(1), mdm(1)
276920200522 2020-05-23 PARALLEL_ALTERNATIVES(7)