Remove tar compress spool from cron email

Question

I have a crontab job that call a simple script to backup a website:

15 0 1,10,20 * * /home/username/bin/backup_whatever

This is the script:

#!/bin/bash
TODAY=$(date +"%Y%m%d")
FILE_TO_PUT="filename.$TODAY.tar.gz"
rm -rf /home/username/filename.tar.gz
tar -zcvf /home/username/filename.tar.gz -C / var/www/website/
s3cmd put /home/username/filename.tar.gz s3://s3bucket/backups/$FILE_TO_PUT

As the tar command compress lots of files, the email I got when this is executed is really huge. How can I do to just display a message like compression successfully instead the full output of tar command?

Will be ok, if I do something like this? Can't find out the tar return codes.

EXITCODE=$(tar -zcvf /home/username/filename.tar.gz -C / var/www/website/)
if [ $EXITCODE -eq 0]
then
    echo "compression successfully"
else
    echo "compression unsuccessfully"
fi

Answer 1

The tar exit codes are documented in the "info" manual - use info tar to read all about tar. (You can read about "info" with info info). It seems there are 3 (major) exit codes. From the info tar documentation:

Possible exit codes of GNU 'tar' are summarized in the following
table:

0
     'Successful termination'.

1
     'Some files differ'.  If tar was invoked with '--compare'
     ('--diff', '-d') command line option, this means that some files in
     the archive differ from their disk counterparts (*note compare::).
     If tar was given '--create', '--append' or '--update' option, this
     exit code means that some files were changed while being archived
     and so the resulting archive does not contain the exact copy of the
     file set.

2
     'Fatal error'.  This means that some fatal, unrecoverable error
     occurred.

   If 'tar' has invoked a subprocess and that subprocess exited with a
nonzero exit code, 'tar' exits with that code as well.  This can happen,
for example, if 'tar' was given some compression option (*note gzip::)
and the external compressor program failed.  Another example is 'rmt'
failure during backup to the remote device (*note Remote Tape Server::).

If you would like to only have a success or failure message of your choice, I'd recommend the following:

tar zcf /home/username/filename.tar.gz -C / var/www/website/ >/dev/null 2>&1
case $? in
    0)
        printf "Complete Success\n"
        ;;
    1)
        printf "Partial Success - some files changed\n"
        ;;
    *)
        printf "Disaster - tar exit code $?\n"
        ;;
esac

This invocation of tar pipes both the standard output and error to /dev/null, a.k.a. the bit bucket. Then the special parameter, $?, which holds the exit status of the most recently executed foreground pipeline, is parsed by the case statement to output the relevant message.