1PARALLEL(1) moreutils PARALLEL(1)
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6 parallel - run programs in parallel
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9 parallel [options] [command]-- [argument ...]
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11 parallel [options]-- [command ...]
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14 parallel runs the specified command, passing it a single one of the
15 specified arguments. This is repeated for each argument. Jobs may be
16 run in parallel. The default is to run one job per CPU.
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18 If no command is specified before the --, the commands after it are
19 instead run in parallel.
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22 -j maxjobs
23 Use to limit the number of jobs that are run at the same time.
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25 -l maxload
26 Wait as needed to avoid starting new jobs when the system's load
27 average is not below the specified limit.
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29 -i
30 Normally the command is passed the argument at the end of its
31 command line. With this option, any instances of "{}" in the
32 command are replaced with the argument.
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34 -n
35 Number of arguments to pass to a command at a time. Default is 1.
36 Incompatible with -i
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39 parallel sh -c "echo hi; sleep 2; echo bye" -- 1 2 3
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41 This runs three subshells that each print a message, delay, and print
42 another message. If your system has multiple CPUs, parallel will run
43 some of the jobs in parallel, which should be clear from the order the
44 messages are output.
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46 parallel -j 3 ufraw -o processed -- *.NEF
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48 This runs three ufraw processes at the same time until all of the NEF
49 files have been processed.
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51 parallel -j 3 -- ls df "echo hi"
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53 This runs three independent commands in parallel.
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56 Its exit status is the combination of the exit statuses of each command
57 ran, ORed together. (Thus, if any one command exits nonzero, parallel
58 as a whole will exit nonzero.)
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61 All output to stdout and stderr is serialised through a corresponding
62 internal pipe, in order to prevent annoying concurrent output
63 behaviour. Note that serialisation is not done on any other file
64 descriptors and file position based access to a nonstandard file
65 descriptor might have unexpected results.
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68 Tollef Fog Heen
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72moreutils 2009-07-02 PARALLEL(1)