Why does the script not work through crontab?

Question

bash

There is a simple script for backup

#!/bin/bash
ssh -2 [email protected] "mysqldump -uUSR -pPASS DB_NAME | gzip -9" > /media/backups/DB-LIVE-$(date +%Y-%m-%d-T%H-%M).sql.gz
ls -t1 /media/backups/ |tail -n +25| xargs rm -f

The table is dumped, all files except the last ones are

deleted
0 * * * * /opt/backup.sh

.
If you run the script manually, then everything works.
Tell me what is the problem when running it through cron.

Answer 1

by default, cron does not use environment variables
in particular PATH
, so it does not know where the interpreter is located

/bin/bash/ls -t1 /media/backups/ |tail -n +25| /bin/bash/xargs rm -f

Answer 2

ls -t1 /media/backups/will only print the filename, not the full path. cd is necessary