Package: cron
Version: 3.0pl1-189
Severity: minor
Tags: patch
Dear Maintainer,
* What led up to the situation?
Checking for defects with
[test-][g|n]roff -mandoc -t -K utf8 -ww -b -z <man page>
[test-groff is a script in the repository for "groff"]
* What was the outcome of this action?
troff: backtrace: file '<stdin>':463
troff:<stdin>:463: warning: special character 'u7A4D' not defined
troff: backtrace: file '<stdin>':463
troff:<stdin>:463: warning: special character 'u4E39' not defined
troff: backtrace: file '<stdin>':463
troff:<stdin>:463: warning: special character 'u5C3C' not defined
* What outcome did you expect instead?
No output (warnings).
-.-
Remarks and a patch are in the attachments.
The concerned man page was autogenerated.
Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
-- System Information:
Debian Release: trixie/sid
APT prefers testing
APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Kernel: Linux 6.7.12-amd64 (SMP w/2 CPU threads; PREEMPT)
Locale: LANG=is_IS.iso88591, LC_CTYPE=is_IS.iso88591 (charmap=ISO-8859-1),
LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: sysvinit (via /sbin/init)
Versions of packages cron depends on:
ii cron-daemon-common 3.0pl1-189
ii init-system-helpers 1.66
ii libc6 2.38-12
ii libpam-runtime 1.5.3-7
ii libpam0g 1.5.3-7
ii libselinux1 3.5-2+b2
ii sensible-utils 0.0.22
Versions of packages cron recommends:
ii exim4-daemon-light [mail-transport-agent] 4.97-8
Versions of packages cron suggests:
ii anacron 2.3-40
pn bat <none>
pn checksecurity <none>
ii logrotate 3.21.0-2
pn supercat <none>
Versions of packages cron is related to:
pn libnss-ldap <none>
pn libnss-ldapd <none>
pn libpam-ldap <none>
pn libpam-mount <none>
pn nis <none>
pn nscd <none>
-- no debconf information
Any program (person), that produces man pages, should check its content for
defects by using
groff -mandoc -t -ww -b -z [ -K utf8 | k ] <man page>
The same goes for man pages that are used as an input.
For a style guide use
mandoc -T lint
-.-
So any generator should check its products with the above mentioned
'groff' and additionally with 'nroff ...'.
This is just a simple quality control measure.
The generator may have to be corrected to get a better man page,
the source file may, and any additional file may.
-.-
The difference between the formatted outputs can be seen with:
nroff -mandoc <file1> > <out1>
nroff -mandoc <file2> > <out2>
diff -u <out1> <out2>
and for groff, using
"printf '%s\n%s\n' '.kern 0' '.ss 12 0' | groff -mandoc -Z - "
instead of "nroff -mandoc"
Add the option "-t", if the file contains a table.
Read the output of "diff -u" with "less -R" or similar.
-.-.
If "man" (man-db) is used to check the manual for warnings,
the following must be set:
The option "-warnings=w"
The environmental variable:
export MAN_KEEP_STDERR=yes (or any non-empty value)
or
(produce only warnings):
export MANROFFOPT="-ww -z"
export MAN_KEEP_STDERR=yes (or any non-empty value)
-.-.
Output from "mandoc -T lint crontab.5": (possibly shortened list)
mandoc: crontab.5:33:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:43:258: STYLE: input text line longer than 80 bytes: Note
that comments o...
mandoc: crontab.5:45:125: STYLE: input text line longer than 80 bytes: An
active line in a ...
mandoc: crontab.5:58:99: STYLE: input text line longer than 80 bytes: where the
spaces aro...
mandoc: crontab.5:63:156: STYLE: input text line longer than 80 bytes: string
may be placed...
mandoc: crontab.5:67:119: STYLE: input text line longer than 80 bytes: string
is not parsed...
mandoc: crontab.5:96:135: STYLE: input text line longer than 80 bytes: There
will not be an...
mandoc: crontab.5:115:114: STYLE: input text line longer than 80 bytes: line of
the crontab\...
mandoc: crontab.5:117:128: STYLE: input text line longer than 80 bytes:
(Another note: the L...
mandoc: crontab.5:121:88: STYLE: input text line longer than 80 bytes: will
look at MAILTO ...
mandoc: crontab.5:123:247: STYLE: input text line longer than 80 bytes:
crontab\&. If MAILTO...
mandoc: crontab.5:131:511: STYLE: input text line longer than 80 bytes: The
format of a cron...
mandoc: crontab.5:135:174: STYLE: input text line longer than 80 bytes: when
the minute, hou...
mandoc: crontab.5:185:144: STYLE: input text line longer than 80 bytes: Ranges
of numbers ar...
mandoc: crontab.5:189:92: STYLE: input text line longer than 80 bytes: Lists
are allowed\&....
mandoc: crontab.5:197:115: STYLE: input text line longer than 80 bytes: can be
used in the h...
mandoc: crontab.5:206:141: STYLE: input text line longer than 80 bytes:
fields\&. Use the fi...
mandoc: crontab.5:210:155: STYLE: input text line longer than 80 bytes: field
(the rest of t...
mandoc: crontab.5:212:263: STYLE: input text line longer than 80 bytes: or by
the shell spec...
mandoc: crontab.5:214:250: STYLE: input text line longer than 80 bytes: Note:
The day of a c...
mandoc: crontab.5:216:228: STYLE: input text line longer than 80 bytes: would
cause a comman...
mandoc: crontab.5:281:164: STYLE: input text line longer than 80 bytes: daemon
startup\&. In...
mandoc: crontab.5:282:2: WARNING: skipping paragraph macro: PP empty
mandoc: crontab.5:283:2: WARNING: skipping paragraph macro: PP empty
mandoc: crontab.5:285:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:318:181: STYLE: input text line longer than 80 bytes: All the
above exampl...
mandoc: crontab.5:335:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:336:147: STYLE: input text line longer than 80 bytes: The
following lists ...
mandoc: crontab.5:370:234: STYLE: input text line longer than 80 bytes: Note
that all the sy...
mandoc: crontab.5:372:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:373:96: STYLE: input text line longer than 80 bytes: In that
example one ...
mandoc: crontab.5:390:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:394:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:395:122: STYLE: input text line longer than 80 bytes: When
specifying day ...
mandoc: crontab.5:397:160: STYLE: input text line longer than 80 bytes: Lists
and ranges are...
mandoc: crontab.5:403:134: STYLE: input text line longer than 80 bytes:
Environment variable...
mandoc: crontab.5:406:251: STYLE: input text line longer than 80 bytes: Command
output is ma...
mandoc: crontab.5:412:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:415:211: STYLE: input text line longer than 80 bytes: daemon
runs with a d...
mandoc: crontab.5:417:275: STYLE: input text line longer than 80 bytes:
environment variable...
mandoc: crontab.5:433:118: STYLE: input text line longer than 80 bytes: POSIX
specifies that...
mandoc: crontab.5:437:165: STYLE: input text line longer than 80 bytes: is a
*\&. This is wh...
mandoc: crontab.5:441:227: STYLE: input text line longer than 80 bytes: syntax
does not make...
mandoc: crontab.5:443:166: STYLE: input text line longer than 80 bytes: syntax,
the best app...
mandoc: crontab.5:445:139: STYLE: input text line longer than 80 bytes: If the
program itsel...
mandoc: crontab.5:462:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:503:2: WARNING: skipping paragraph macro: PP empty
mandoc: crontab.5:505:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:506:255: STYLE: input text line longer than 80 bytes: cron
requires that e...
mandoc: crontab.5:508:2: WARNING: skipping paragraph macro: PP after SH
mandoc: crontab.5:534:2: WARNING: skipping paragraph macro: br after SH
mandoc: crontab.5:538:503: STYLE: input text line longer than 80 bytes:
Distribute freely, e...
mandoc: crontab.5:540:109: STYLE: input text line longer than 80 bytes: Since
year 1994, man...
-.-.
Remove space characters at the end of lines.
Use "git apply ... --whitespace=fix" to fix extra space issues, or use
global configuration "core.whitespace".
52:
312:
328:
364:
383:
427:
455:
472:
485:
498:
-.-.
Mark a full stop (.) and the exclamation mark (!) with "\&",
if it does not mean an end of a sentence.
This is a preventive action,
the paragraph could be reshaped, e.g., after changes.
When typing, one does not always notice when the line wraps after the
period.
There are too many examples of input lines in manual pages,
that end with an abbreviation point.
This marking is robust, and independent of the position on the line.
It corresponds to "\ " in TeX, and to "@:" in Texinfo.
117:(Another note: the LOGNAME variable is sometimes called USER on BSD
systems\&.\&.\&. on these systems, USER will be set also\&.)
397:Lists and ranges are allowed to co\-exist in the same field\&. "1\-3,7\-9"
would be rejected by AT&T or BSD cron \-\- they want to see "1\-3" or "7,8,9"
ONLY\&.
506:cron requires that each entry in a crontab end in a newline character\&. If
the last entry in a crontab is missing a newline (i\&.e\&. terminated by EOF),
cron will consider the crontab (at least partially) broken\&. A warning will be
written to syslog\&.
-.-.
Add a (no-break, "\ " or "\~") space between a number and a unit,
as these are not one entity.
297:# run at 2:15pm on the first of every month \-\- output mailed to paul
300:0 22 * * 1\-5 mail \-s "It\*(Aqs 10pm" joe%Joe,%%Where are your kids?%
-.-.
Wrong distance between sentences.
Separate the sentences and subordinate clauses; each begins on a new
line. See man-pages(7) ("Conventions for source file layout") and
"info groff" ("Input Conventions").
The best procedure is to always start a new sentence on a new line,
at least, if you are typing on a computer.
Remember coding: Only one command ("sentence") on each (logical) line.
E-mail: Easier to quote exactly the relevant lines.
Generally: Easier to edit the sentence.
Patches: Less unaffected text.
Search for two adjacent words is easier, when they belong to the same line,
and the same phrase.
The amount of space between sentences in the output can then be
controlled with the ".ss" request.
N.B.
The number of lines affected can be too large to be in the patch.
39:\(lqrun this command at this time on this date\(rq\&. Each user has their
own crontab, and commands in any given crontab will be executed as the user who
owns the crontab\&. Uucp and News will usually have their own crontabs,
eliminating the need for explicitly running
43:Note that comments on the same line as cron commands are not interpreted as
comments in the cron sense, but are considered part of the command and passed
to the shell\&. This is similarly true for comments on the same line as
environment variable settings\&.
45:An active line in a crontab will be either an environment setting or a cron
command\&. An environment setting is of the form,
61:\fIname\fR\&. The
63:string may be placed in quotes (single or double, but matching) to preserve
leading or trailing blanks\&. To define an empty variable, quotes can be used\&.
81:will not work as you might expect\&. And neither will this work
96:There will not be any substitution for the defined variables in the last
value\&. However, with most shells you can also try e\&.g\&.,:
112:daemon\&. SHELL is set to
115:line of the crontab\*(Aqs owner\&. HOME and SHELL may be overridden by
settings in the crontab; LOGNAME may not\&.
117:(Another note: the LOGNAME variable is sometimes called USER on BSD
systems\&.\&.\&. on these systems, USER will be set also\&.)
123:crontab\&. If MAILTO is defined (and non\-empty), mail is sent to the user
so named\&. If MAILTO is defined but empty (MAILTO=""), no mail will be sent\&.
Otherwise mail is sent to the owner of the crontab\&. This option is useful if
you decide on
131:The format of a cron command is very much the V7 standard, with a number of
upward\-compatible extensions\&. Each line has five time and date fields,
followed by a command, followed by a newline character (\*(Aq\en\*(Aq)\&. The
system crontab (/etc/crontab) uses the same format, except that the username
for the command is specified after the time and date fields and before the
command\&. The fields may be separated by spaces or tabs\&. The maximum
permitted length for the command field is 998 characters\&.
139:examines cron entries once every minute\&. The time and date fields are:
185:Ranges of numbers are allowed\&. Ranges are two numbers separated with a
hyphen\&. The specified range is inclusive\&. For example, 8\-11 for an
189:Lists are allowed\&. A list is a set of numbers (or ranges) separated by
commas\&. Examples:
193:Step values can be used in conjunction with ranges\&. Following a range with
195:specifies skips of the number\*(Aqs value through the range\&. For example,
198:\(lq0,2,4,6,8,10,12,14,16,18,20,22\(rq)\&. Steps are also permitted after
an asterisk, so if you want to say
206:fields\&. Use the first three letters of the particular day or month (case
doesn\*(Aqt matter)\&. Ranges or lists of names are not allowed\&.
210:field (the rest of the line) specifies the command to be run\&. The entire
command portion of the line, up to a newline or % character, will be executed by
212:or by the shell specified in the SHELL variable of the cronfile\&.
Percent\-signs (%) in the command, unless escaped with backslash (\e), will be
changed into newline charac\(hy ters, and all data after the first % will be
sent to the command as standard input\&.
214:Note: The day of a command\*(Aqs execution can be specified by two fields
\(em day of month, and day of week\&. If both fields are restricted (i\&.e\&.,
aren\*(Aqt *), the command will be run when either field matches the current
time\&. For example,
216:would cause a command to be run at 4:30 am on the 1st and 15th of each
month, plus every Friday\&. One can, however, achieve the desired result by
adding a test to the command (see the last example in EXAMPLE CRON FILE
below)\&.
281:daemon startup\&. In particular, it may be before some system daemons, or
other facilities, were startup\&. This is due to the boot order sequence of the
machine\&.
318:All the above examples run non\-interactive programs\&. If you wish to run
a program that interacts with the user\*(Aqs desktop you have to make sure the
proper environment variable
336:The following lists the content of a regular system\-wide crontab file\&.
Unlike a user\*(Aqs crontab, this file has the username field, as used by
370:Note that all the system\-wide tasks will run, by default, from 6 am to 7
am\&. In the case of systems that are not powered on during that period of
time, only the hourly tasks will be executed unless the defaults above are
changed\&.
395:When specifying day of week, both day 0 and day 7 will be considered
Sunday\&. BSD and AT&T seem to disagree about this\&.
397:Lists and ranges are allowed to co\-exist in the same field\&. "1\-3,7\-9"
would be rejected by AT&T or BSD cron \-\- they want to see "1\-3" or "7,8,9"
ONLY\&.
403:Environment variables can be set in the crontab\&. In BSD or AT&T, the
environment handed to child processes is basically the one from
415:daemon runs with a defined timezone\&. It currently does not support
per\-user timezones\&. All the tasks: system\*(Aqs and user\*(Aqs will be run
based on the configured timezone\&. Even if a user specifies the
417:environment variable in his crontab this will affect only the commands
executed in the crontab, not the execution of the crontab tasks them\(hy
selves\&. If one wants to specify a particular timezone for crontab tasks, one
may check the date in the child script, for example:
435:a *\&. However, this implementation only checks if the
437:is a *\&. This is why "0 0 */2 * sun" runs every Sunday that\*(Aqs an
uneven date while the POSIX standard would have it run every Sunday and on
every uneven date\&.
441:syntax does not make it possible to define all possible periods one can
imagine\&. For example, it is not straightforward to define the last weekday of
a month\&. To have a task run in a time period that cannot be defined using
445:If the program itself cannot do the checks then a wrapper script would be
required\&. Useful tools that could be used for date analysis are
448:\fIcalendar\fR\&. For example, to run a program the last Saturday of every
month you could use the following wrapper code:
478:it won\*(Aqt work without the eval\&. Saying
506:cron requires that each entry in a crontab end in a newline character\&. If
the last entry in a crontab is missing a newline (i\&.e\&. terminated by EOF),
cron will consider the crontab (at least partially) broken\&. A warning will be
written to syslog\&.
538:Distribute freely, except: don\*(Aqt remove my name from the source or
documentation (don\*(Aqt take credit for my work), mark your changes (don\*(Aqt
get me blamed for your possible bugs), don\*(Aqt alter or remove this notice\&.
May be sold if buildable source is provided to buyer\&. No warranty of any
kind, express or implied, is included with this software; use at your own risk,
responsibility for damages (if any) to anyone resulting from the use of this
software rests entirely with the user\&.
-.-.
Split lines longer than 80 characters into two or more lines.
Appropriate break points are the end of a sentence and a subordinate
clause; after punctuation marks.
N.B.
The number of lines affected can be too large to be in the patch.
Line 39, length 269
\(lqrun this command at this time on this date\(rq\&. Each user has their own
crontab, and commands in any given crontab will be executed as the user who
owns the crontab\&. Uucp and News will usually have their own crontabs,
eliminating the need for explicitly running
Line 43, length 258
Note that comments on the same line as cron commands are not interpreted as
comments in the cron sense, but are considered part of the command and passed
to the shell\&. This is similarly true for comments on the same line as
environment variable settings\&.
Line 45, length 125
An active line in a crontab will be either an environment setting or a cron
command\&. An environment setting is of the form,
Line 58, length 99
where the spaces around the equal\-sign (=) are optional, and any subsequent
non\-leading spaces in
Line 63, length 156
string may be placed in quotes (single or double, but matching) to preserve
leading or trailing blanks\&. To define an empty variable, quotes can be used\&.
Line 67, length 119
string is not parsed for environmental substitutions or replacement of
variables or tilde(~) expansion, thus lines like
Line 96, length 135
There will not be any substitution for the defined variables in the last
value\&. However, with most shells you can also try e\&.g\&.,:
Line 115, length 114
line of the crontab\*(Aqs owner\&. HOME and SHELL may be overridden by settings
in the crontab; LOGNAME may not\&.
Line 117, length 128
(Another note: the LOGNAME variable is sometimes called USER on BSD
systems\&.\&.\&. on these systems, USER will be set also\&.)
Line 121, length 88
will look at MAILTO if it has any reason to send mail as a result of running
commands in
Line 123, length 247
crontab\&. If MAILTO is defined (and non\-empty), mail is sent to the user so
named\&. If MAILTO is defined but empty (MAILTO=""), no mail will be sent\&.
Otherwise mail is sent to the owner of the crontab\&. This option is useful if
you decide on
Line 131, length 511
The format of a cron command is very much the V7 standard, with a number of
upward\-compatible extensions\&. Each line has five time and date fields,
followed by a command, followed by a newline character (\*(Aq\en\*(Aq)\&. The
system crontab (/etc/crontab) uses the same format, except that the username
for the command is specified after the time and date fields and before the
command\&. The fields may be separated by spaces or tabs\&. The maximum
permitted length for the command field is 998 characters\&.
Line 135, length 174
when the minute, hour, and month of year fields match the current time, and
when at least one of the two day fields (day of month, or day of week) match
the current time (see
Line 185, length 144
Ranges of numbers are allowed\&. Ranges are two numbers separated with a
hyphen\&. The specified range is inclusive\&. For example, 8\-11 for an
Line 189, length 92
Lists are allowed\&. A list is a set of numbers (or ranges) separated by
commas\&. Examples:
Line 197, length 115
can be used in the hours field to specify command execution every other hour
(the alternative in the V7 standard is
Line 198, length 108
\(lq0,2,4,6,8,10,12,14,16,18,20,22\(rq)\&. Steps are also permitted after an
asterisk, so if you want to say
Line 206, length 141
fields\&. Use the first three letters of the particular day or month (case
doesn\*(Aqt matter)\&. Ranges or lists of names are not allowed\&.
Line 210, length 155
field (the rest of the line) specifies the command to be run\&. The entire
command portion of the line, up to a newline or % character, will be executed by
Line 212, length 263
or by the shell specified in the SHELL variable of the cronfile\&.
Percent\-signs (%) in the command, unless escaped with backslash (\e), will be
changed into newline charac\(hy ters, and all data after the first % will be
sent to the command as standard input\&.
Line 214, length 250
Note: The day of a command\*(Aqs execution can be specified by two fields \(em
day of month, and day of week\&. If both fields are restricted (i\&.e\&.,
aren\*(Aqt *), the command will be run when either field matches the current
time\&. For example,
Line 216, length 228
would cause a command to be run at 4:30 am on the 1st and 15th of each month,
plus every Friday\&. One can, however, achieve the desired result by adding a
test to the command (see the last example in EXAMPLE CRON FILE below)\&.
Line 281, length 164
daemon startup\&. In particular, it may be before some system daemons, or other
facilities, were startup\&. This is due to the boot order sequence of the
machine\&.
Line 308, length 84
0 4 * * * Sat d=$(date +e) && test $d \-ge 8 \-a $d \-le 14 && echo "2nd
Saturday"
Line 318, length 181
All the above examples run non\-interactive programs\&. If you wish to run a
program that interacts with the user\*(Aqs desktop you have to make sure the
proper environment variable
Line 336, length 147
The following lists the content of a regular system\-wide crontab file\&.
Unlike a user\*(Aqs crontab, this file has the username field, as used by
Line 357, length 93
# | | | | \&.\-\-\-\- day of week (0 \- 6) (Sunday=0 or 7) OR
sun,mon,tue,wed,thu,fri,sat
Line 360, length 99
25 6 * * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts \-\-report
/etc/cron\&.daily )
Line 361, length 100
47 6 * * 7 root test \-x /usr/sbin/anacron || ( cd / && run\-parts \-\-report
/etc/cron\&.weekly )
Line 362, length 101
52 6 1 * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts \-\-report
/etc/cron\&.monthly )
Line 370, length 234
Note that all the system\-wide tasks will run, by default, from 6 am to 7 am\&.
In the case of systems that are not powered on during that period of time, only
the hourly tasks will be executed unless the defaults above are changed\&.
Line 373, length 96
In that example one can see that numbers can be prepended some 0, in order to
line up columns\&.
Line 380, length 100
25 16 * * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.daily )
Line 381, length 101
47 06 * * 7 root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.weekly )
Line 382, length 102
52 06 1 * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.monthly )
Line 395, length 122
When specifying day of week, both day 0 and day 7 will be considered Sunday\&.
BSD and AT&T seem to disagree about this\&.
Line 397, length 160
Lists and ranges are allowed to co\-exist in the same field\&. "1\-3,7\-9"
would be rejected by AT&T or BSD cron \-\- they want to see "1\-3" or "7,8,9"
ONLY\&.
Line 403, length 134
Environment variables can be set in the crontab\&. In BSD or AT&T, the
environment handed to child processes is basically the one from
Line 406, length 251
Command output is mailed to the crontab owner (BSD can\*(Aqt do this), can be
mailed to a person other than the crontab owner (SysV can\*(Aqt do this), or
the feature can be turned off and no mail will be sent at all (SysV can\*(Aqt
do this either)\&.
Line 415, length 211
daemon runs with a defined timezone\&. It currently does not support per\-user
timezones\&. All the tasks: system\*(Aqs and user\*(Aqs will be run based on
the configured timezone\&. Even if a user specifies the
Line 417, length 275
environment variable in his crontab this will affect only the commands executed
in the crontab, not the execution of the crontab tasks them\(hy selves\&. If
one wants to specify a particular timezone for crontab tasks, one may check the
date in the child script, for example:
Line 433, length 118
POSIX specifies that the day of month and the day of week fields both need to
match the current time if either of them
Line 437, length 165
is a *\&. This is why "0 0 */2 * sun" runs every Sunday that\*(Aqs an uneven
date while the POSIX standard would have it run every Sunday and on every
uneven date\&.
Line 441, length 227
syntax does not make it possible to define all possible periods one can
imagine\&. For example, it is not straightforward to define the last weekday of
a month\&. To have a task run in a time period that cannot be defined using
Line 443, length 166
syntax, the best approach would be to have the program itself check the date
and time information and continue execution only if the period matches the
desired one\&.
Line 445, length 139
If the program itself cannot do the checks then a wrapper script would be
required\&. Useful tools that could be used for date analysis are
Line 448, length 122
\fIcalendar\fR\&. For example, to run a program the last Saturday of every
month you could use the following wrapper code:
Line 454, length 150
0 4 * * Sat [ "$(date +\e%e)" = "$(LANG=C ncal | sed \-n \*(Aqs/^Sa \&.*
\e([0\-9]\e+\e) *$/\e1/p\*(Aq)" ] && echo "Last Saturday" && program_to_run
Line 506, length 255
cron requires that each entry in a crontab end in a newline character\&. If the
last entry in a crontab is missing a newline (i\&.e\&. terminated by EOF), cron
will consider the crontab (at least partially) broken\&. A warning will be
written to syslog\&.
Line 538, length 503
Distribute freely, except: don\*(Aqt remove my name from the source or
documentation (don\*(Aqt take credit for my work), mark your changes (don\*(Aqt
get me blamed for your possible bugs), don\*(Aqt alter or remove this notice\&.
May be sold if buildable source is provided to buyer\&. No warranty of any
kind, express or implied, is included with this software; use at your own risk,
responsibility for damages (if any) to anyone resulting from the use of this
software rests entirely with the user\&.
Line 540, length 109
Since year 1994, many modifications were made in this manpage, authored by
Debian Developers which maintained
-.-.
Use the name of units in text; use symbols in tables and
calculations.
The rule is to have a (no-break, \~) space between a number and
its units (see "www.bipm.org/en/publications/si-brochure")
297:# run at 2:15pm on the first of every month \-\- output mailed to paul
301:23 0\-23/2 * * * echo "run 23 minutes after midn, 2am, 4am \&.\&.\&.,
everyday"
-.-.
Show if docman-to-man created this
4:.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
-.-.
Output from "test-groff -b -mandoc -rF0 -rHY=0 -K utf8 -t -ww -z ":
troff: backtrace: file '<stdin>':463
troff:<stdin>:463: warning: special character 'u7A4D' not defined
troff: backtrace: file '<stdin>':463
troff:<stdin>:463: warning: special character 'u4E39' not defined
troff: backtrace: file '<stdin>':463
troff:<stdin>:463: warning: special character 'u5C3C' not defined
--- crontab.5 2024-06-09 01:16:20.033661930 +0000
+++ crontab.5.new 2024-06-09 03:33:03.996557398 +0000
@@ -30,26 +30,35 @@
.SH "NAME"
crontab \- tables for driving cron
.SH "DESCRIPTION"
-.PP
A
\fIcrontab\fR
file contains instructions to the
\fBcron\fR(8)
daemon of the general form:
-\(lqrun this command at this time on this date\(rq\&. Each user has their own
crontab, and commands in any given crontab will be executed as the user who
owns the crontab\&. Uucp and News will usually have their own crontabs,
eliminating the need for explicitly running
-\fBsu\fR(1)
-as part of a cron command\&.
+\(lqrun this command at this time on this date\(rq.
+Each user has their own crontab,
+and commands in any given crontab will be executed as the user who
+owns the crontab.
+Uucp and News will usually have their own crontabs,
+eliminating the need for explicitly running \fBsu\fR(1)
+as part of a cron command.
.PP
-Note that comments on the same line as cron commands are not interpreted as
comments in the cron sense, but are considered part of the command and passed
to the shell\&. This is similarly true for comments on the same line as
environment variable settings\&.
+Note that comments on the same line as cron commands are not interpreted as
+comments in the cron sense,
+but are considered part of the command and passed to the shell.
+This is similarly true for comments on the same line as environment variable
+settings.
.PP
-An active line in a crontab will be either an environment setting or a cron
command\&. An environment setting is of the form,
+An active line in a crontab will be either an environment setting or a cron
+command.
+An environment setting is of the form,
.sp
.if n \{\
.RS 4
.\}
.nf
name = value
-
+
.fi
.if n \{\
.RE
@@ -58,13 +67,17 @@ name = value
where the spaces around the equal\-sign (=) are optional, and any subsequent
non\-leading spaces in
\fIvalue\fR
will be part of the value assigned to
-\fIname\fR\&. The
-\fIvalue\fR
-string may be placed in quotes (single or double, but matching) to preserve
leading or trailing blanks\&. To define an empty variable, quotes can be used\&.
+\fIname\fR.
+The \fIvalue\fR string may be placed in quotes
+(single or double, but matching)
+to preserve leading or trailing blanks.
+To define an empty variable, quotes can be used.
.PP
The
\fIvalue\fR
-string is not parsed for environmental substitutions or replacement of
variables or tilde(~) expansion, thus lines like
+string is not parsed for environmental substitutions or replacement of
+variables or tilde(~) expansion,
+thus lines like
.sp
.if n \{\
.RS 4
@@ -78,7 +91,7 @@ PATH=~/bin:/usr/bin
.RE
.\}
.sp
-will not work as you might expect\&. And neither will this work
+will not work as you might expect. And neither will this work
.sp
.if n \{\
.RS 4
@@ -93,7 +106,9 @@ C=$A $B
.RE
.\}
.sp
-There will not be any substitution for the defined variables in the last
value\&. However, with most shells you can also try e\&.g\&.,:
+There will not be any substitution for the defined variables in the last
+value.
+However, with most shells you can also try e.g.,:
.sp
.if n \{\
.RS 4
@@ -109,34 +124,52 @@ P=PATH=/a/b/c:$PATH
.sp
Several environment variables are set up automatically by the
\fBcron\fR(8)
-daemon\&. SHELL is set to
+daemon. SHELL is set to
/usr/bin/sh, and LOGNAME and HOME are set from the
/etc/passwd
-line of the crontab\*(Aqs owner\&. HOME and SHELL may be overridden by
settings in the crontab; LOGNAME may not\&.
+line of the crontab\*(Aqs owner.
+HOME and SHELL may be overridden by settings in the crontab; LOGNAME may not.
.PP
-(Another note: the LOGNAME variable is sometimes called USER on BSD
systems\&.\&.\&. on these systems, USER will be set also\&.)
+(Another note: the LOGNAME variable is sometimes called USER on BSD
+systems...\& on these systems, USER will be set also.)
.PP
In addition to LOGNAME, HOME, and SHELL,
\fBcron\fR(8)
will look at MAILTO if it has any reason to send mail as a result of running
commands in
-\(lqthis\(rq
-crontab\&. If MAILTO is defined (and non\-empty), mail is sent to the user so
named\&. If MAILTO is defined but empty (MAILTO=""), no mail will be sent\&.
Otherwise mail is sent to the owner of the crontab\&. This option is useful if
you decide on
-\fB/usr/bin/mail\fR
+\(lqthis\(rq crontab.
+If MAILTO is defined (and non\-empty),
+mail is sent to the user so named.
+If MAILTO is defined but empty (MAILTO=""),
+no mail will be sent.
+Otherwise mail is sent to the owner of the crontab.
+This option is useful if you decide on \fB/usr/bin/mail\fR
instead of
\fB/usr/lib/sendmail\fR
as your mailer when you install cron \-\-
-\fB/usr/bin/mail\fR
-doesn\*(Aqt do aliasing, and UUCP usually doesn\*(Aqt read its mail\&.
+\fB/usr/bin/mail\fR doesn\*(Aqt do aliasing,
+and UUCP usually doesn\*(Aqt read its mail.
.PP
-The format of a cron command is very much the V7 standard, with a number of
upward\-compatible extensions\&. Each line has five time and date fields,
followed by a command, followed by a newline character (\*(Aq\en\*(Aq)\&. The
system crontab (/etc/crontab) uses the same format, except that the username
for the command is specified after the time and date fields and before the
command\&. The fields may be separated by spaces or tabs\&. The maximum
permitted length for the command field is 998 characters\&.
+The format of a cron command is very much the V7 standard, with a number of
+upward\-compatible extensions.
+Each line has five time and date fields,
+followed by a command,
+followed by a newline character (\*(Aq\en\*(Aq).
+The system crontab (/etc/crontab) uses the same format,
+except that the username
+for the command is specified after the time and date fields and before the
+command.
+The fields may be separated by spaces or tabs.
+The maximum permitted length for the command field is 998 characters.
.PP
Commands are executed by
\fBcron\fR(8)
-when the minute, hour, and month of year fields match the current time, and
when at least one of the two day fields (day of month, or day of week) match
the current time (see
-\(lqNote\(rq
-below)\&.
+when the minute, hour, and month of year fields match the current time,
+and when at least one of the two day fields
+(day of month, or day of week)
+match the current time
+(see \(lqNote\(rq below).
\fBcron\fR(8)
-examines cron entries once every minute\&. The time and date fields are:
+examines cron entries once every minute. The time and date fields are:
.TS
allbox tab(:);
lB lB.
@@ -180,42 +213,66 @@ T}
.sp 1
.PP
A field may be an asterisk (*), which always stands for
-\(lqfirst\-last\(rq\&.
+\(lqfirst\-last\(rq.
.PP
-Ranges of numbers are allowed\&. Ranges are two numbers separated with a
hyphen\&. The specified range is inclusive\&. For example, 8\-11 for an
-\(lqhours\(rq
-entry specifies execution at hours 8, 9, 10 and 11\&.
+Ranges of numbers are allowed.
+Ranges are two numbers separated with a hyphen.
+The specified range is inclusive.
+For example, 8\-11 for an \(lqhours\(rq
+entry specifies execution at hours 8, 9, 10 and 11.
.PP
-Lists are allowed\&. A list is a set of numbers (or ranges) separated by
commas\&. Examples:
+Lists are allowed.
+A list is a set of numbers (or ranges) separated by commas.
+Examples:
\(lq1,2,5,9\(rq,
-\(lq0\-4,8\-12\(rq\&.
+\(lq0\-4,8\-12\(rq.
.PP
-Step values can be used in conjunction with ranges\&. Following a range with
-\(lq/<number>\(rq
-specifies skips of the number\*(Aqs value through the range\&. For example,
-\(lq0\-23/2\(rq
-can be used in the hours field to specify command execution every other hour
(the alternative in the V7 standard is
-\(lq0,2,4,6,8,10,12,14,16,18,20,22\(rq)\&. Steps are also permitted after an
asterisk, so if you want to say
-\(lqevery two hours\(rq, just use
-\(lq*/2\(rq\&.
+Step values can be used in conjunction with ranges.
+Following a range with \(lq/<number>\(rq
+specifies skips of the number\*(Aqs value through the range.
+For example, \(lq0\-23/2\(rq
+can be used in the hours field to specify command execution every other hour
+(the alternative in the V7 standard is
+\(lq0,2,4,6,8,10,12,14,16,18,20,22\(rq).
+Steps are also permitted after an asterisk,
+so if you want to say \(lqevery two hours\(rq,
+just use \(lq*/2\(rq.
.PP
-Names can also be used for the
-\(lqmonth\(rq
-and
-\(lqday of week\(rq
-fields\&. Use the first three letters of the particular day or month (case
doesn\*(Aqt matter)\&. Ranges or lists of names are not allowed\&.
+Names can also be used for the \(lqmonth\(rq and
+\(lqday of week\(rq fields.
+Use the first three letters of the particular day or month
+(case doesn\*(Aqt matter).
+Ranges or lists of names are not allowed.
.PP
-The
-\(lqsixth\(rq
-field (the rest of the line) specifies the command to be run\&. The entire
command portion of the line, up to a newline or % character, will be executed by
-\fB/usr/bin/sh\fR
-or by the shell specified in the SHELL variable of the cronfile\&.
Percent\-signs (%) in the command, unless escaped with backslash (\e), will be
changed into newline charac\(hy ters, and all data after the first % will be
sent to the command as standard input\&.
+The \(lqsixth\(rq field
+(the rest of the line)
+specifies the command to be run.
+The entire command portion of the line,
+up to a newline or % character,
+will be executed by \fB/usr/bin/sh\fR
+or by the shell specified in the SHELL variable of the cronfile.
+Percent\-signs (%) in the command,
+unless escaped with backslash (\e),
+will be changed into newline characters,
+and all data after the first % will
+be sent to the command as standard input.
.PP
-Note: The day of a command\*(Aqs execution can be specified by two fields \(em
day of month, and day of week\&. If both fields are restricted (i\&.e\&.,
aren\*(Aqt *), the command will be run when either field matches the current
time\&. For example,
+Note: The day of a command\*(Aqs execution can be specified by two fields
+\(em day of month, and day of week.
+If both fields are restricted
+(i.e., aren\*(Aqt *),
+the command will be run when either field matches the current time.
+For example,
\(lq30 4 1,15 * 5\(rq
-would cause a command to be run at 4:30 am on the 1st and 15th of each month,
plus every Friday\&. One can, however, achieve the desired result by adding a
test to the command (see the last example in EXAMPLE CRON FILE below)\&.
+would cause a command to be run at 4:30 am on the 1st and 15th of each
+month,
+plus every Friday.
+One can, however, achieve the desired result by
+adding a test to the command
+(see the last example in EXAMPLE CRON FILE below).
.PP
Instead of the first five fields, one of eight special strings may appear:
+.nr col_width \w'Run once a month, "0 0 1 * *".'
.TS
allbox tab(:);
lB lB.
@@ -225,23 +282,16 @@ T}:T{
meaning
T}
.T&
-l l
-l l
-l l
-l l
-l l
-l l
-l l
-l l.
+l lw(\n[col_width]u).
T{
@reboot
T}:T{
-Run once, at startup\&.
+Run once, at startup.
T}
T{
@yearly
T}:T{
-Run once a year, "0 0 1 1 *"\&.
+Run once a year, "0 0 1 1 *".
T}
T{
@annually
@@ -251,17 +301,17 @@ T}
T{
@monthly
T}:T{
-Run once a month, "0 0 1 * *"\&.
+Run once a month, "0 0 1 * *".
T}
T{
@weekly
T}:T{
-Run once a week, "0 0 * * 0"\&.
+Run once a week, "0 0 * * 0".
T}
T{
@daily
T}:T{
-Run once a day, "0 0 * * *"\&.
+Run once a day, "0 0 * * *".
T}
T{
@midnight
@@ -271,18 +321,17 @@ T}
T{
@hourly
T}:T{
-Run once an hour, "0 * * * *"\&.
+Run once an hour, "0 * * * *".
T}
.TE
.sp 1
.PP
Please note that startup, as far as @reboot is concerned, is the time when the
-\fBcron\fR(8)
-daemon startup\&. In particular, it may be before some system daemons, or
other facilities, were startup\&. This is due to the boot order sequence of the
machine\&.
-.PP
-.PP
+\fBcron\fR(8) daemon startup.
+In particular, it may be before some system daemons, or
+other facilities, were startup.
+This is due to the boot order sequence of the machine.
.SH "EXAMPLE CRON FILE"
-.PP
.if n \{\
.RS 4
.\}
@@ -293,12 +342,12 @@ SHELL=/usr/bin/sh
MAILTO=paul
#
# run five minutes after midnight, every day
-5 0 * * * $HOME/bin/daily\&.job >> $HOME/tmp/out 2>&1
-# run at 2:15pm on the first of every month \-\- output mailed to paul
+5 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
+# run at 2:15\~pm on the first of every month \-\- output mailed to paul
15 14 1 * * $HOME/bin/monthly
# run at 10 pm on weekdays, annoy Joe
-0 22 * * 1\-5 mail \-s "It\*(Aqs 10pm" joe%Joe,%%Where are your kids?%
-23 0\-23/2 * * * echo "run 23 minutes after midn, 2am, 4am \&.\&.\&., everyday"
+0 22 * * 1\-5 mail \-s "It\*(Aqs 10\~pm" joe%Joe,%%Where are your kids?%
+23 0\-23/2 * * * echo "run 23 minutes after midn, 2\~am, 4\~am \&..., everyday"
5 4 * * sun echo "run at 5 after 4 every Sunday"
0 */4 1 * mon echo "run every 4th hour on the 1st and on every Monday"
0 0 */2 * sun echo "run at midn on every Sunday that\*(Aqs an uneven date"
@@ -309,15 +358,17 @@ MAILTO=paul
#Execute early the next morning following the first
#Thursday of each month
57 2 * * 5 case $(date +d) in 0[2\-8]) echo "After 1st Thursday"; esac
-
+
.fi
.if n \{\
.RE
.\}
.PP
-All the above examples run non\-interactive programs\&. If you wish to run a
program that interacts with the user\*(Aqs desktop you have to make sure the
proper environment variable
+All the above examples run non\-interactive programs.
+If you wish to run a program that interacts with the user\*(Aqs desktop you
+have to make sure the proper environment variable
\fIDISPLAY\fR
-is set\&.
+is set.
.sp
.if n \{\
.RS 4
@@ -325,16 +376,15 @@ is set\&.
.nf
# Execute a program and run a notification every day at 10:00 am
0 10 * * * $HOME/bin/program | DISPLAY=:0 notify\-send "Program run" "$(cat)"
-
+
.fi
.if n \{\
.RE
.\}
-.sp
.SH "EXAMPLE SYSTEM CRON FILE"
-.PP
-The following lists the content of a regular system\-wide crontab file\&.
Unlike a user\*(Aqs crontab, this file has the username field, as used by
-/etc/crontab\&.
+The following lists the content of a regular system\-wide crontab file.
+Unlike a user\*(Aqs crontab,
+this file has the username field, as used by /etc/crontab.
.sp
.if n \{\
.RS 4
@@ -343,8 +393,8 @@ The following lists the content of a reg
# /etc/crontab: system\-wide crontab
# Unlike any other crontab you don\*(Aqt have to run the `crontab\*(Aq
# command to install the new version when you edit this file
-# and files in /etc/cron\&.d\&. These files also have username fields,
-# that none of the other crontabs do\&.
+# and files in /etc/cron.d. These files also have username fields,
+# that none of the other crontabs do.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
@@ -353,68 +403,84 @@ PATH=/usr/local/sbin:/usr/local/bin:/sbi
# \&.\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- minute (0 \- 59)
# | \&.\-\-\-\-\-\-\-\-\-\-\-\-\- hour (0 \- 23)
# | | \&.\-\-\-\-\-\-\-\-\-\- day of month (1 \- 31)
-# | | | \&.\-\-\-\-\-\-\- month (1 \- 12) OR jan,feb,mar,apr \&.\&.\&.
+# | | | \&.\-\-\-\-\-\-\- month (1 \- 12) OR jan,feb,mar,apr \&...
# | | | | \&.\-\-\-\- day of week (0 \- 6) (Sunday=0 or 7) OR
sun,mon,tue,wed,thu,fri,sat
# m h dom mon dow usercommand
-17 * * * * root cd / && run\-parts \-\-report /etc/cron\&.hourly
-25 6 * * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.daily )
-47 6 * * 7 root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.weekly )
-52 6 1 * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.monthly )
+17 * * * * root cd / && run\-parts \-\-report /etc/cron.hourly
+25 6 * * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron.daily )
+47 6 * * 7 root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron.weekly )
+52 6 1 * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron.monthly )
#
-
+
.fi
.if n \{\
.RE
.\}
.PP
-Note that all the system\-wide tasks will run, by default, from 6 am to 7
am\&. In the case of systems that are not powered on during that period of
time, only the hourly tasks will be executed unless the defaults above are
changed\&.
+Note that all the system\-wide tasks will run, by default,
+from 6 am to 7 am.
+In the case of systems that are not powered on during that period of
+time,
+only the hourly tasks will be executed unless the defaults above are changed.
.SH "YET ANOTHER EXAMPLE"
-.PP
-In that example one can see that numbers can be prepended some 0, in order to
line up columns\&.
+In that example one can see that numbers can be prepended some 0,
+in order to line up columns.
.sp
.if n \{\
.RS 4
.\}
.nf
-17 * * * * root cd / && run\-parts \-\-report /etc/cron\&.hourly
-25 16 * * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.daily )
-47 06 * * 7 root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.weekly )
-52 06 1 * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron\&.monthly )
-
+17 * * * * root cd / && run\-parts \-\-report /etc/cron.hourly
+25 16 * * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron.daily )
+47 06 * * 7 root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron.weekly )
+52 06 1 * * root test \-x /usr/sbin/anacron || ( cd / && run\-parts
\-\-report /etc/cron.monthly )
+
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
-.PP
\fBcron\fR(8),
\fBcrontab\fR(1)
.SH "EXTENSIONS"
+When specifying day of week, both day 0 and day 7 will be considered Sunday.
+BSD and AT&T seem to disagree about this.
.PP
-When specifying day of week, both day 0 and day 7 will be considered Sunday\&.
BSD and AT&T seem to disagree about this\&.
-.PP
-Lists and ranges are allowed to co\-exist in the same field\&. "1\-3,7\-9"
would be rejected by AT&T or BSD cron \-\- they want to see "1\-3" or "7,8,9"
ONLY\&.
+Lists and ranges are allowed to co\-exist in the same field.
+"1\-3,7\-9" would be rejected by AT&T or BSD cron \-\-
+they want to see "1\-3" or "7,8,9" ONLY.
.PP
-Ranges can include "steps", so "1\-9/2" is the same as "1,3,5,7,9"\&.
+Ranges can include "steps", so "1\-9/2" is the same as "1,3,5,7,9".
.PP
-Names of months or days of the week can be specified by name\&.
+Names of months or days of the week can be specified by name.
.PP
-Environment variables can be set in the crontab\&. In BSD or AT&T, the
environment handed to child processes is basically the one from
-/etc/rc\&.
+Environment variables can be set in the crontab.
+In BSD or AT&T,
+the environment handed to child processes is basically the one from /etc/rc.
.PP
-Command output is mailed to the crontab owner (BSD can\*(Aqt do this), can be
mailed to a person other than the crontab owner (SysV can\*(Aqt do this), or
the feature can be turned off and no mail will be sent at all (SysV can\*(Aqt
do this either)\&.
+Command output is mailed to the crontab owner
+(BSD can\*(Aqt do this),
+can be mailed to a person other than the crontab owner
+(SysV can\*(Aqt do this),
+or the feature can be turned off and no mail will be sent at all
+(SysV can\*(Aqt do this either).
.PP
All of the
\(lq@\(rq
-commands that can appear in place of the first five fields are extensions\&.
+commands that can appear in place of the first five fields are extensions.
.SH "LIMITATIONS"
-.PP
The
\fBcron\fR
-daemon runs with a defined timezone\&. It currently does not support per\-user
timezones\&. All the tasks: system\*(Aqs and user\*(Aqs will be run based on
the configured timezone\&. Even if a user specifies the
-\fITZ\fR
-environment variable in his crontab this will affect only the commands
executed in the crontab, not the execution of the crontab tasks them\(hy
selves\&. If one wants to specify a particular timezone for crontab tasks, one
may check the date in the child script, for example:
+daemon runs with a defined timezone.
+It currently does not support per\-user timezones.
+All the tasks: system\*(Aqs and user\*(Aqs will be run based on the
+configured timezone.
+Even if a user specifies the \fITZ\fR environment variable in his crontab
+this will affect only the commands executed in the crontab,
+not the execution of the crontab tasks themselves.
+If one wants to specify a particular timezone for crontab tasks,
+one may check the date in the child script, for example:
.sp
.if n \{\
.RS 4
@@ -424,42 +490,50 @@ environment variable in his crontab this
TZ=UTC
0 * * * * [ "$(date +\e%R)" = 00:00 ] && run_some_script
-
+
.fi
.if n \{\
.RE
.\}
.PP
-POSIX specifies that the day of month and the day of week fields both need to
match the current time if either of them
-\fIis\fR
-a *\&. However, this implementation only checks if the
-\fIfirst character\fR
-is a *\&. This is why "0 0 */2 * sun" runs every Sunday that\*(Aqs an uneven
date while the POSIX standard would have it run every Sunday and on every
uneven date\&.
+POSIX specifies that the day of month and the day of week fields both need
+to match the current time if either of them \fIis\fR a *.
+However, this implementation only checks if the \fIfirst character\fR is a *.
+This is why "0 0 */2 * sun" runs every Sunday that\*(Aqs an uneven date
+while the POSIX standard would have it run every Sunday and on every uneven
+date.
.PP
The
\fIcrontab\fR
-syntax does not make it possible to define all possible periods one can
imagine\&. For example, it is not straightforward to define the last weekday of
a month\&. To have a task run in a time period that cannot be defined using
-\fIcrontab\fR
-syntax, the best approach would be to have the program itself check the date
and time information and continue execution only if the period matches the
desired one\&.
+syntax does not make it possible to define all possible periods one can
+imagine.
+For example,
+it is not straightforward to define the last weekday of a month.
+To have a task run in a time period that cannot be defined using
+\fIcrontab\fR syntax,
+the best approach would be to have the program itself check the date and
+time information and
+continue execution only if the period matches the desired one.
.PP
-If the program itself cannot do the checks then a wrapper script would be
required\&. Useful tools that could be used for date analysis are
-\fIncal\fR
+If the program itself cannot do the checks
+then a wrapper script would be required.
+Useful tools that could be used for date analysis are \fIncal\fR
or
-\fIcalendar\fR\&. For example, to run a program the last Saturday of every
month you could use the following wrapper code:
+\fIcalendar\fR.
+For example, to run a program the last Saturday of every month you could use
+the following wrapper code:
.sp
.if n \{\
.RS 4
.\}
.nf
0 4 * * Sat [ "$(date +\e%e)" = "$(LANG=C ncal | sed \-n \*(Aqs/^Sa \&.*
\e([0\-9]\e+\e) *$/\e1/p\*(Aq)" ] && echo "Last Saturday" && program_to_run
-
+
.fi
.if n \{\
.RE
.\}
-.sp
.SH "USING EVAL TO WRAP MISC ENVIRONMENT SETTINGS"
-.PP
The following tip is kindly provided by ç©ä¸¹å°¼ Dan Jacobson:
.sp
.if n \{\
@@ -467,22 +541,22 @@ The following tip is kindly provided by
.\}
.nf
CONTENT_TYPE="text/plain; charset=UTF\-8"
-d=eval LANG=zh_TW\&.UTF\-8 w3m \-dump
-26 22 16 1\-12 * $d https://www\&.ptt\&.cc/bbs/transgender/index\&.html
-
+d=eval LANG=zh_TW.UTF\-8 w3m \-dump
+26 22 16 1\-12 * $d https://www.ptt.cc/bbs/transgender/index.html
+
.fi
.if n \{\
.RE
.\}
.PP
-it won\*(Aqt work without the eval\&. Saying
+it won\*(Aqt work without the eval. Saying
.sp
.if n \{\
.RS 4
.\}
.nf
-d=LANG=zh_TW\&.UTF\-8 w3m \-dump
-
+d=LANG=zh_TW.UTF\-8 w3m \-dump
+
.fi
.if n \{\
.RE
@@ -494,50 +568,58 @@ will get
.RS 4
.\}
.nf
-/bin/sh: LANG=zh_TW\&.UTF\-8: command not found
-
+/bin/sh: LANG=zh_TW.UTF\-8: command not found
+
.fi
.if n \{\
.RE
.\}
-.PP
.SH "DIAGNOSTICS"
-.PP
-cron requires that each entry in a crontab end in a newline character\&. If
the last entry in a crontab is missing a newline (i\&.e\&. terminated by EOF),
cron will consider the crontab (at least partially) broken\&. A warning will be
written to syslog\&.
+cron requires that each entry in a crontab end in a newline character.
+If the last entry in a crontab is missing a newline
+(i.e.\& terminated by EOF),
+cron will consider the crontab (at least partially) broken.
+A warning will be written to syslog.
.SH "AUTHORS"
-.PP
-\fBPaul Vixie\fR <\&paul@vix\&.com\&>
+\fBPaul Vixie\fR <\&[email protected]\&>
.RS 4
-Wrote this manpage (1994)\&.
+Wrote this manpage (1994).
.RE
.PP
-\fBSteve Greenland\fR <\&stevegr@debian\&.org\&>
+\fBSteve Greenland\fR <\&[email protected]\&>
.RS 4
-Maintained the package (1996\-2005)\&.
+Maintained the package (1996\-2005).
.RE
.PP
-\fBJavier Fern\('andez\-Sanguino Pe\(~na\fR <\&jfs@debian\&.org\&>
+\fBJavier Fern\('andez\-Sanguino Pe\(~na\fR <\&[email protected]\&>
.RS 4
-Maintained the package (2005\-2014)\&.
+Maintained the package (2005\-2014).
.RE
.PP
-\fBChristian Kastner\fR <\&ckk@debian\&.org\&>
+\fBChristian Kastner\fR <\&[email protected]\&>
.RS 4
-Maintained the package (2010\-2016)\&.
+Maintained the package (2010\-2016).
.RE
.PP
-\fBGeorges Khaznadar\fR <\&georgesk@debian\&.org\&>
+\fBGeorges Khaznadar\fR <\&[email protected]\&>
.RS 4
-Maintained the package (2022\-2024)\&.
+Maintained the package (2022\-2024).
.RE
.SH "COPYRIGHT"
-.br
Copyright \(co 1994 Paul Vixie
-.br
.PP
-Distribute freely, except: don\*(Aqt remove my name from the source or
documentation (don\*(Aqt take credit for my work), mark your changes (don\*(Aqt
get me blamed for your possible bugs), don\*(Aqt alter or remove this notice\&.
May be sold if buildable source is provided to buyer\&. No warranty of any
kind, express or implied, is included with this software; use at your own risk,
responsibility for damages (if any) to anyone resulting from the use of this
software rests entirely with the user\&.
+Distribute freely, except:
+don\*(Aqt remove my name from the source or documentation
+(don\*(Aqt take credit for my work),
+mark your changes
+(don\*(Aqt get me blamed for your possible bugs),
+don\*(Aqt alter or remove this notice.
+May be sold if buildable source is provided to buyer.
+No warranty of any kind, express or implied, is included with this software;
+use at your own risk, responsibility for damages (if any) to anyone resulting
+from the use of this software rests entirely with the user.
.PP
-Since year 1994, many modifications were made in this manpage, authored by
Debian Developers which maintained
-cron; above is a short list, more information can be found in the file
-/usr/share/doc/cron/copyright\&.
-.sp
+Since year 1994, many modifications were made in this manpage,
+authored by Debian Developers which maintained cron;
+above is a short list,
+more information can be found in the file /usr/share/doc/cron/copyright.
