From: Georges Khaznadar Date: Sun, 27 Oct 2024 16:53:53 +0100 Subject: more_examples_for_crontab This patch modifies crontab.5 in order to give useful information about: - using eval command, which makes easier to express environment assignments inside commands to call with cron. - using leading zeroes instead of spaces to line up columns --- crontab.1 | 25 ++++++++++++++++++++++++- crontab.5 | 31 ++++++++++++++++++++++++++++--- spcrc-crontab | 42 ++++++++++++++++++++++++++++++++++++++++++ spcrc-crontab-light | 44 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 138 insertions(+), 4 deletions(-) create mode 100644 spcrc-crontab create mode 100644 spcrc-crontab-light diff --git a/crontab.1 b/crontab.1 index 2c87bc9..9da1e16 100644 --- a/crontab.1 +++ b/crontab.1 @@ -139,8 +139,31 @@ original behaviour by setting the environment variable to 'N', which will cause the .I crontab \-l command to emit the extraneous header. +.SH HIGHLIGHTING THE OUTPUT of crontab \-l +The command +.I crontab \-l +outputs plain text. When a tty can support ANSI sequences to colourise +this text, one can highlight the output, by calling: +.I crontab \-l | spc -t crontab +when the tty background is dark, or +.I crontab \-l | spc -t crontab-light +when this background is light. +.PP +The highlighting scheme can be modified by using customised versions of +files +.I /etc/supercat/spcrc-crontab* +.PP +One can also colourise this text with the program +.I batcat +provided by the package +.I bat +, here is an example: +.nf +.I crontab \-l | batcat --language Crontab +.fi + .SH "SEE ALSO" -crontab(5), cron(8) +crontab(5), cron(8), spc(1) .SH FILES .nf /etc/cron.allow diff --git a/crontab.5 b/crontab.5 index 15f9fef..b3f3d15 100644 --- a/crontab.5 +++ b/crontab.5 @@ -64,8 +64,8 @@ tilde(~) expansion, thus lines like .PP .in +4n .nf -PATH = $HOME/bin:$PATH -PATH = ~/bin:/usr/bin +PATH=$HOME/bin:$PATH +PATH=~/bin:/usr/bin .fi .in .PP @@ -80,7 +80,10 @@ C=$A $B .in .PP There will not be any substitution for the defined variables in the -last value. +last value. However, with most shells you can also try e.g.,: +.PP + P=PATH=/a/b/c:$PATH + 33 22 1 2 3 eval $P && some commands .PP Several environment variables are set up automatically by the .IR cron (8) @@ -290,6 +293,17 @@ Note that all the system-wide tasks will run, by default, from 6 am to 7 am. In the case of systems that are not powered on during that period of time, only the hourly tasks will be executed unless the defaults above are changed. +.SH YET ANOTHER EXAMPLE + +In that example one can see that numbers can be prepended some 0, in order +to line up columns. + +.nf +17 * * * * root cd / && run-parts --report /etc/cron.hourly +25 16 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ) +47 06 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly ) +52 06 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly ) +.fi .SH SEE ALSO cron(8), crontab(1) @@ -367,6 +381,17 @@ the following wrapper code: 0 4 * * Sat [ "$(date +\e%e)" = "$(LANG=C ncal | sed \-n 's/^Sa .* \e([0\-9]\e+\e) *$/\e1/p')" ] && echo "Last Saturday" && program_to_run .fi +.SH USING EVAL TO WRAP MISC ENVIRONMENT SETTINGS +The following tip is kindly provided by 積丹尼 Dan Jacobson: +.PP + 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 +.PP + it won't work without the eval. Saying + d=LANG=zh_TW.UTF-8 w3m -dump + will get + /bin/sh: LANG=zh_TW.UTF-8: command not found .SH DIAGNOSTICS cron requires that each entry in a crontab end in a newline character. If the diff --git a/spcrc-crontab b/spcrc-crontab new file mode 100644 index 0000000..8c0f147 --- /dev/null +++ b/spcrc-crontab @@ -0,0 +1,42 @@ +# ============ this file is to colorize crontabs ========== +# 1 2 3 4 5 +#2345678901234567890123456789012345678901234567890123456789 +# HTML COLOR COL A N T STRING or REGULAR EXPRESSION +#################### ### # # # ############################ +#Where: +# HTML COLOR - Standard HTML Color name for HTML output +# COL - Console color name from the list +# red, yel, cya, grn, mag, blk, whi, blu +# A - Attribute from the list +# ' ' : normal +# 'b' : bold +# 'u' : underline +# 'r' : reverse video +# 'k' : blink +# N - number of matches +# ' ' : all +# '0' : all +# '1' - '9' : number of matches +# T - type of matching to perform +# 'c' : characters +# 's' : string +# 'r' : regex - case sensitive +# 'R' : regex - case insensitive +# 't' : regex with Unix time conversion +# ' ' : default ('r' regex) +# 1 2 3 4 5 +#2345678901234567890123456789012345678901234567890123456789 +# HTML COLOR COL A N T STRING or REGULAR EXPRESSION +#################### ### # # # ############################ +# dom is blue + bold +Blue blu b 5 \s+(\S+) +# month is green + bold +Green grn b 4 \s+(\S+) +# dow is green + reverse video +Green grn r 3 \s+(\S+) +# hour is red + bold +Red red b 2 \s+(\S+) +# minute is red + reverse video +Red red r 1 \s*(\S+) +# comments are magenta +Magenta mag (^#.*) diff --git a/spcrc-crontab-light b/spcrc-crontab-light new file mode 100644 index 0000000..81de807 --- /dev/null +++ b/spcrc-crontab-light @@ -0,0 +1,44 @@ +# ============ this file is to colorize crontabs ========== +# 1 2 3 4 5 +#2345678901234567890123456789012345678901234567890123456789 +# HTML COLOR COL A N T STRING or REGULAR EXPRESSION +#################### ### # # # ############################ +#Where: +# HTML COLOR - Standard HTML Color name for HTML output +# COL - Console color name from the list +# red, yel, cya, grn, mag, blk, whi, blu +# A - Attribute from the list +# ' ' : normal +# 'b' : bold +# 'u' : underline +# 'r' : reverse video +# 'k' : blink +# N - number of matches +# ' ' : all +# '0' : all +# '1' - '9' : number of matches +# T - type of matching to perform +# 'c' : characters +# 's' : string +# 'r' : regex - case sensitive +# 'R' : regex - case insensitive +# 't' : regex with Unix time conversion +# ' ' : default ('r' regex) +# 1 2 3 4 5 +#2345678901234567890123456789012345678901234567890123456789 +# HTML COLOR COL A N T STRING or REGULAR EXPRESSION +#################### ### # # # ############################ +# default is black +Black blk (.*) +# dom is blue + bold +Blue blu b 5 \s+(\S+) +# month is green + bold +Green grn b 4 \s+(\S+) +# dow is green + reverse video +Green grn r 3 \s+(\S+) +# hour is red + bold +Red red b 2 \s+(\S+) +# minute is red + reverse video +Red red r 1 \s*(\S+) +# comments are magenta +Magenta mag (^#.*)