[Chapter 40] 40.15 crontab Script Makes crontab Editing Easier/Safer

40.15 crontab Script Makes crontab Editing Easier/Safer

crontab	I've made mistakes with the crontab command, accidentally deleting my crontab file and not being able to get it back. I like the SunOS crontab -e command for interactive editing. So, I made a shell script that does it. To help keep me from using the system version, I store this script in a directory near the start of my PATH ( 8.7 ) ; if I really need the system version, I type its absolute pathname.

I've made mistakes with the crontab command, accidentally deleting my crontab file and not being able to get it back. I like the SunOS crontab -e command for interactive editing. So, I made a shell script that does it. To help keep me from using the system version, I store this script in a directory near the start of my PATH ( 8.7 ) ; if I really need the system version, I type its absolute pathname.

umask trap || ${..-..} cmp

#! /bin/sh cmd=/usr/bin/crontab # THE SYSTEM VERSION # MAKE SURE EVERYONE KNOWS WHAT THEY'RE RUNNING: echo "Running Jerry's crontab command..." 1>&2 case $# in 1) ;; # OK *) echo "Usage: `/bin/basename $0` -e | -l | -d"; exit 1 ;; esac case "$1" in -[ld]) $cmd $1 ;; # EXIT WITH STATUS OF REAL COMMAND -e) # EDIT IT: umask 077 stat=1 # DEFAULT EXIT STATUS; RESET TO 0 FOR NORMAL EXIT start=/tmp/CRONTAB$$s end=/tmp/CRONTAB$$e trap 'rm -f $start $end; exit $stat' 0 1 2 15 $cmd -l > $start || exit # GET COPY OF CRONTAB /bin/cp $start $end ${VISUAL-${EDITOR-vi}} $end if cmp -s $start $end then echo "The crontab file was not changed." 1>&2; exit else $cmd $end stat=$? # EXIT WITH STATUS FROM REAL crontab COMMAND exit fi ;; *) echo "Usage: `/bin/basename $0` -e | -l | -d"; exit 1;; esac

umask trap \|\| ${..-..} cmp	#! /bin/sh cmd=/usr/bin/crontab # THE SYSTEM VERSION # MAKE SURE EVERYONE KNOWS WHAT THEY'RE RUNNING: echo "Running Jerry's crontab command..." 1>&2 case $# in 1) ;; # OK ) echo "Usage: `/bin/basename $0` -e \| -l \| -d"; exit 1 ;; esac case "$1" in -[ld]) $cmd $1 ;; # EXIT WITH STATUS OF REAL COMMAND -e) # EDIT IT: umask 077 stat=1 # DEFAULT EXIT STATUS; RESET TO 0 FOR NORMAL EXIT start=/tmp/CRONTAB$$s end=/tmp/CRONTAB$$e trap 'rm -f $start $end; exit $stat' 0 1 2 15 $cmd -l > $start \|\| exit # GET COPY OF CRONTAB /bin/cp $start $end ${VISUAL-${EDITOR-vi}} $end if cmp -s $start $end then echo "The crontab file was not changed." 1>&2; exit else $cmd $end stat=$? # EXIT WITH STATUS FROM REAL crontab COMMAND exit fi ;; ) echo "Usage: `/bin/basename $0` -e \| -l \| -d"; exit 1;; esac

- JP


40.14 Including Standard Input Within a cron Entry		VII. Terminals and Printers