Crontab Editing in a shell script

[tekpr00]

Hello All:

I have a shell script that should open a crontab and add a new line and save after. However I cannot make it work. Any suggestion will be appreciated.

cron.sh
crontab -l > oracle.cron.20100509
newline="the contents of the new crontab line"
(crontab -l; echo "$newline") | crontab -

however the above gave me an error:
$ ./cron.sh
crontab: can't open your crontab file.
./cron.sh: line 2: 1177 Broken Pipe crontab -l

Please help

 

[feherke]

Hi

There are two [tt]crontab[/tt] instances running in the same time, one is reading the crontab file, the other is trying to write it. But of course fails.

Fortunately you are creating a copy of the crontab file. So use that instead :

crontab -l [teal]>[/teal] oracle[teal].[/teal]cron[teal].[/teal][purple]20100509[/purple]
[navy]newline[/navy][teal]=[/teal][green][i]"the contents of the new crontab line"[/i][/green]
[teal]([/teal][highlight]cat oracle[teal].[/teal]cron[teal].[/teal][purple]20100509[/purple][/highlight][teal];[/teal] echo [green][i]"$newline"[/i][/green][teal])[/teal] [teal]|[/teal] crontab -

Feherke.

http://free.rootshell.be/~feherke/

 

[Annihilannic]

Another approach using the line-based ex editor:

crontab -l > oracle.cron.$(date +%Y%m%d)

echo '$a
00 05 * * * /usr/bin/true a new cron job
.
wq' | EDITOR=ex crontab -e

Annihilannic.

 

[SamBones]

Why not this?

NEWJOB="0 12 * * * /path/to/newjob parameters"

crontab -l > crontab.dat
cat $NEWJOB >> crontab.dat
crontab crontab.dat

Simple, no editing to get working correctly. Just get the current crontab, append the line, then make it the current crontab.