1SWATCH(1) User Contributed Perl Documentation SWATCH(1)
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6 swatch - simple watcher
7
9 swatch [ --awk-field-syntax ] [ --config-file⎪-c file ] [ --daemon ] [
10 --extra-include-dir⎪-I path ] [ --extra-module⎪-M module_name ] [
11 --help⎪-h ] [ --input-record-separator regex ] [ --old-style-config⎪-O
12 ] [ --pid-file file ] [ --restart-time⎪-r time ] [ --script-dir path ]
13 [ --tail-args arguments_for_tail_program ] [ --tail-program-name file‐
14 name ] [ --version⎪-V ] [ --use-cpan-file-tail ] [ [ --examine⎪-f
15 file_to_examine ] ⎪ [ --read-pipe⎪-p program_to_pipe_from ] ⎪ [
16 --tail-file⎪-t file_to_tail ] ] [ --debug [ level ] ] [ --dump-script
17 filename ]
18
20 Swatch is designed to monitor system activity. In order for Swatch to
21 be useful, it requires a configuration file which contains pattern(s)
22 to look for and action(s) to perform when each pattern is found.
23
25 --awk-field-syntax
26 Use this option only if you want to overide regular expression
27 backreferencing in favor of awk(1) style field referencing.
28 Included for backward compatability.
29 --config-file⎪-c filename
31 Tells swatch where to find its configuration file. The default is
32 ${HOME}/.swatchrc.
33 --daemon
35 This tells swatch to run in the background and disassociate itself
36 from any terminal.
37 --extra-include-dir⎪-I path
39 This tells swatch where to look for custom action modules.
40 --extra-module⎪-M module_name
42 This tells swatch what custom action modules to load in.
43 --help⎪-h
45 Prints usage information and exits.
46 --input-record-separator=regular_expression
48 Tells swatch to use regular_expression to delineate the boundary of
49 each input record. The default is a carriage return.
50 --old-style-config⎪-O
52 This tells swatch that your configuration file is written using the
53 syntax that was abandoned back in the 1990's.
54 --pid-file file
56 Writes the process ID to file. Useful when running in daemon mode.
57 --restart-time=[+]hh:mm[am⎪pm] or -r [+]hh:mm[am⎪pm]
59 Restart at the specified time where hh is hours and mm is minutes.
60 If the am/pm indicator is omitted, then a 24-hour clock is assumed.
61 If the time is preceded by the "+" character, then the restart time
62 will be set to the current time plus the specified time and the
63 am/pm indicator will be ignored.
64 --script-dir=/path/to/directory
66 This switch causes the temporary watcher script to be written to a
67 file in the specified directory rather than the user's home direc‐
68 tory. It is highly advised that you do NOT use directories that are
69 writable by others such as /tmp.
70 --tail-args arguments_for_tail_program
72 Pass specific options to the tail(1) program.
73 --tail-program-name filename
75 Runs an alternate tail(1) like program instead of the system
76 default.
77 --version or -V
79 Prints version information and exits.
80 --use-cpan-file-tail
82 Use CPAN's File::Tail module to read the log file instead of the
83 tail(1) command.
84 You may specify only one of the following options:
86 --tail-file=filename or -t filename
88 Examine lines of text as they are added to filename.
89 --read-pipe=command or -p command
91 Examine input piped in from the command.
92 --examine=filename or -f filename
94 Use filename as the file to examine. Swatch will do a single pass
95 through the named file.
96 The following options are purely for debugging purposes, but are docu‐
98 mented here for completeness:
99 --debug[=level]
101 Spew out various levels of debugging for swatch developers.
102 --dump-script[=filename]
104 Instead of running the watcher script after it is generated, it is
105 written to filename or to STDOUT.
106 If swatch is called with no options, it is the same as typing the com‐
108 mand line
109 swatch --config-file=~/.swatchrc --tail-file=/var/log/syslog
111 or if /var/log/messages exists
113 swatch --config-file=~/.swatchrc --tail-file=/var/log/messages
115
117 The configuration file is used by the swatch(8) program to determine
118 what types of expression patterns to look for and what type of
119 action(s) should be taken when a pattern is matched.
120 Each line should contain a keyword and a, sometimes optional, value for
122 that keyword. The keyword and value are separated by a space or an
123 equal (=) sign.
124 watchfor regex
126 ignore regex
128 echo [modes]
130 Echo the matched line. The text mode may be normal, bold, under‐
131 score, blink, inverse, black, red, green, yellow, blue, magenta,
132 cyan, white, black_h, red_h, green_h, yellow_h, blue_h, magenta_h,
133 cyan_h, and/or white_h. The _h colors specify a highlighting color.
134 The other colors are assigned to the letters. Some modes may not
135 work on some terminals. Normal is the default.
136 bell [N]
138 Echo the matched line, and send a bell N times (default = 1).
139 exec command
141 Execute command. The command may contain variables which are sub‐
142 stituted with fields from the matched line. A $N will be replaced
143 by the Nth field in the line. A $0 or $* will be replaced by the
144 entire line.
145 mail [addresses=address:address:...][,subject=your_text_here]
147 Send mail to address(es) containing the matched lines as they
148 appear (default address is the user who is running the program).
149 pipe command[,keep_open]
151 Pipe matched lines into command. Use the keep_open option to force
152 the pipe to stay open until a different pipe action is run or until
153 swatch exits.
154 write [user:user:...]
156 Use write(1) to send matched lines to user(s).
157 throttle hours:minutes:seconds,[key=message⎪regex⎪<regexE]>
159 This action has been depreciated. Use threshold instead For exam‐
160 ple,
161 throttle 15:00,key="foo"
163 would look like this
165 threshold track_by="foo",type=limit,count=1,seconds=900
167 threshold track_by=key, type=<limit⎪threshold⎪both, count=number, sec‐
169 onds=number>
170 Thresholding can be done for the complete watchfor block and/or for
171 individual actions. Add "threshold=on" as an option along with the
172 other threshold options when thresholding an individual action.
173 track_by
175 The value of this should be something that is unique to the
176 watchfor regular expression. Tip: enclose unique parts of the
177 regular expression in parentheses, then use the sub matches as
178 part of the value (e.g. track_by="$2:$4").
179 type
181 There are three types of thresholding. They are as follows:
182 limit
184 Perform action(s) for the first "count" matches during the
185 time interval specified by "seconds", then ignore events
186 for the rest of the time interval (kind of like throttle)
187 threshold
189 Perform action(s) on each match for up to count matches
190 during the time interval specified by seconds
191 both
193 Perform actions(s) once per time interval after "count"
194 matches occur, then ignore additional matches during the
195 time interval specified by "seconds"
196 continue
198 Use this action to cause swatch to continue to try to match other
199 pattern/action groups after it is done with the current pat‐
200 tern/action block.
201 quit
203 Use this action to cause swatch to clean up and quit immediately.
204
206 The following may be used as an option for any of the above actions
207 except for throttle and threshold.
208 when=day_of_week:hour_of_day
210 Use this option to specify windows of time and days when the action
211 can be performed. For example:
212 mail=sysad-pager@somehost.somedomain,when=1-6:8-17
214
216 perlcode [depth] arbitrary_Perl_code
217 This permits you to easily insert random Perl code into your
218 swatchrc file. The optional depth value tells swatch how deep into
219 the code to put the perl code. (0=outside the main loop, 1=inside
220 the main loop (default), 2=just inside the conditional used by the
221 current watchfor statement, and 3=inside the throttle block).
222 Its intended use is to permit variable substitution. For example:
224 perlcode $syslog="^\w{3}\s+\d{1,2}\s+\d{2}:\d{2}:\d{2}.*";
226 watchfor /$syslog hostname pppd/>
228 but any valid Perl is permitted. Remember the semicolon, and make
230 judicious use of the --dump-script option if you run into trouble.
231
233 In this example, a line which contains the string "file system full"
234 will be echoed and the screen bell will sound. Also, threshold will
235 use what is matched within the parentheses as its key rather than try‐
236 ing to use the log message with its time stamp cut out. Multiple
237 instances of the message will not be echoed if they appear within a
238 minute of the first one. Instead the following message will be acted
239 upon after the time interval has expired.
240
242 signal(3), perl(1), perlre(1)
243
245 Upon receiving an ALRM or HUP signal swatch will re-read the configura‐
246 tion file and restart, except when used with the --daemon command line
247 option where it will simply exit. Swatch will terminate gracefully
248 when it receives a QUIT, TERM, or INT signal.
249
251 E. Todd Atkins
252 Todd.Atkins@StanfordAlumni.ORG
253
255 Swatch is a SourceForge project whose project page is at http://source‐
256 forge.net/projects/swatch and homepage is at http://swatch.source‐
257 forge.net
258perl v5.8.8 2006-07-21 SWATCH(1)