Cron job isn't writing to log file

Question

I have a shell script that writes the date to a log file when executed. When I run the script manually, the correct output gets written to the file. However, this needs to be automated, and when I run as a cron job, nothing is getting written to the file and I am confused why.

crontab:

0 * * * * tomcat /usr/bin/sh /apps/rdsreplication/snap_replication.sh

Sample Code:

#/bin/bash/

echo ---------------------------------------- >> create_snap.txt
echo Start time:  >> create_snap.txt
date >> create_snap.txt

Any help would be appreciated!

Solution

The shell script needs to use the full path for the log file:

#/bin/bash/
# assuming you want the txt file in the same directory as the bash script
logfile="$(dirname "$0")/create_snap.txt"
{
    echo ----------------------------------------
    echo Start time:
    date 
} >> "$logfile"

Comments

[thrig]

What working directory pwd does cron run things under?

[roaima]

1. Do you actually have a /usr/bin/sh? This is an unusual location for a shell. 2. Which crontab file are you using, or how are you adding this line to cron? 3. What gets reported in cron's log file (typically somewhere in /var/log) for this job?

[roaima]

@thrig it's the user account's home directory

[AndG]

@roaima yes, on this server I ran which sh, and that was the path returned. I am using the tomcat user's crontab, I am adding the line using crontab -e. /var/log/cron shows this: Mar 1 18:06:01 sonar CROND[1585]: (tomcat) CMD (/usr/bin/sh /apps/rdsreplication/snap_replication.sh)

[Ulrich Schwarz]

@roaima: many systemd-based distros have /bin as a symlink to /usr/bin nowadays, since it is no longer possible to have /usr on a separate partition anyway.

[roaima]

@UlrichSchwarz I was thinking of Solaris (not used it for years, though)

[thrig]

@roaima maybe. But what directory is that? NULL on account of Active Directory doing lord knows what? Flapping between what LDAP is providing and a local account, depending on the whims of sssd or such?

[AndG]

I tried this, but the date is still not getting written to the log file. I am assuming this is because it is running out of /home/tomcat/ and not /apps/rdsreplication/ where the log file resides? I think if I add this line to the script it should work: cd /apps/rdsreplication/.

[roaima]

@N.M.D I haven't seen your script or your system's setup so I can't comment on good locations to run the script from. The cron entry will be run from the user acccount's home directory, so if the script can't run from there it needs to change directory - or you need to use cd /correct/path && sh /apps/.../snap_replication.sh.