Shell Programming and Scripting

Hi ,

what is the simple way to do the following :

i would search in a crontab file for specific string of characters (ex: toto.ksh) and only on this line change the beginning as follows :
00 23 * * 0
with
00 23 * * 3
or maybe 2 changes:
with
10 23 * * 3

thanks in advance

Christian

Hmmm.... Is it really worth (potentially) risking knackering your crontab with a script?

Why don't you just use crontab -e? (Or are you running it for a lot of users?) But to answer your question, I'd probably rather use awk than sed to modify specific fields.

Cheers
ZB

Well i'm working for 2 users and about 60 servers.
I 1st send a remote script to save the crontab on each but i would apply the same modification on all of them !


but what i want could be on others types of files not only crontab !

Christian

Hi ,

well i think i must associate grep and awk commands but don't know how !!!

my original text file is :

# Purge des logs et fichiers temporaires
# ------------------------------------------
00 23 * * * ksh -c '. $HOME/.kshrc;$PRCCOM/sys_purge_fic.ksh' > /tmp/sys_purge_fic_notes01.log 2>&1
#
# Lancement de commandes NOTES , fichier en entrée /users/notes01/scripts/sad/dat/notes_cmd_maint.dat
# NE PAS OUBLIER de commenter la ligne pour des commandes temporaires
#--------------------------------------------------------------------------------------------------
#
00 23 * * 3 /users/notes01/scripts/sad/util/notes_cmd_maint.ksh
#



and want to change only a part of 1 line like this :



# Purge des logs et fichiers temporaires
# ------------------------------------------
00 23 * * * ksh -c '. $HOME/.kshrc;$PRCCOM/sys_purge_fic.ksh' > /tmp/sys_purge_fic_notes01.log 2>&1
#
# Lancement de commandes NOTES , fichier en entrée /users/notes01/scripts/sad/dat/notes_cmd_maint.dat
# NE PAS OUBLIER de commenter la ligne pour des commandes temporaires
#--------------------------------------------------------------------------------------------------
#
15 23 * * 4 /users/notes01/scripts/sad/util/notes_cmd_maint.ksh
#

YES it's extracted from crontab file but i save the original one before modifying it !

thanks in advance , it would be great ! it would avoid me to modify manually 60 server's crontab !!!!!

regards

Christian

For your needs, this would work...

Code:

#!/bin/sh

cp crontab crontab.old

awk '{ if ( $0 ~ /notes_cmd_maint.ksh/ ) 
	{ print "15 23 * * 4 " $6 } 
       else { print $0 } 
     }' crontab.old > crontab

exit 0

You'll need to adjust the paths to crontab to whatever suits you.

Cheers
ZB

Thanks for your help !

...but if in the same line i would only modify "notes01" with "notes02" , i must use i think the BEGIN statement
but the following doesn't work !

awk '{ if ( $0 ~ /notes_cmd_maint.ksh/ )
BEGIN {FS="\/"} { print $1"/"$2"/"notes02""/"$4 "/"$5"/"$6 }
else { print $0 }
}' crontab-160904 > crontab-160904-new

exit 0



regards

Christian

Include a "sub"stitute.....

Code:

awk '{ if ( $0 ~ /notes_cmd_maint.ksh/ ) 
	{ gsub( /notes01/, "notes02", $6); print "15 23 * * 4 " $6 } 
       else { print $0 } 
     }' crontab.old > crontab

Cheers
ZB