For some reason, my backup is not working, when it is started by cron.

Crontab entry

0 10 * * * /home/yzT/BackupDaily.sh



/home/yzT/Tools/FreeFileSync/FreeFileSync /home/yzT/Tools/FreeFileSync/BackupDaily.ffs_batch

I can see cron starting my backup script in syslog.

Oct 20 10:00:01 debian CRON[2589]: (yzT) CMD (/home/yzT/BackupDaily.sh)

When I run it manually, the backup system (FreeFileSystem) creates a log file on my Desktop and I can see updated files in the backup directory. But via cron I do not get a logfile nor see any updates.

How can I find/fix the problem?


I found the root of the problem. Switched to TTY and run the script, and I get the following message: Error: Unable to initialize GTK+, is DISPLAY set properly?. So, although there is no GUI using the script, it seems the script wants to have access to the GUI application. How can I fix this?

  • What makes you think it hasn't run ? @Freds suggestion to output a line into a logfile would be a useful diagnostic tool. In BackupDaily.sh you could add (echo "Backup daily running"; date)>>/home/yzT/bkup.log
    – X Tian
    Oct 20, 2015 at 10:05
  • Compare your interactive env with the cron one. Probably something missing, causing the FreeFileSync to error out
    – Jeff Schaller
    Oct 20, 2015 at 10:15
  • @XTian because the BackupDaily.ffs_batch actually saves a log file on Desktop, and it's not there. And however, if I manually run the script, it is. And basically... because there is no changes at the destination.
    – user27807
    Oct 20, 2015 at 12:06

3 Answers 3


If you are the only user on the system, you can just edit your crontab (with crontab -e) and add DISPLAY=:0.0 at the top of the file.

Alternatively, you can try running your backup job like so:

/home/yzT/Tools/FreeFileSync/FreeFileSync /home/yzT/Tools/FreeFileSync/BackupDaily.ffs_batch --display=:0.0

  • ok, now it works. Just for the record, the --display=:0.0 version doesn't work, but adding DISPLAY=:0.0does work.
    – user27807
    Oct 20, 2015 at 19:40
  • On Debian, I had to and "env DISPLAY=:0.0" at the begging to make it work. As in " * * * * env DISPLAY=:0.0 /home/yzT/Tools/FreeFileSync/FreeFileSync /home/yzT/Tools/FreeFileSync/BackupDaily.ffs_batch"
    – Damon
    Feb 2, 2017 at 6:01

Files with extension .ffs_batch are an xml text associated with FreeFileSync app. Therefore, there are two correct ways to program it in cron (crontab -e):

export DISPLAY=:0; /path_to/FreeFileSync /path_to/file.ffs_batch


/path_to/FreeFileSync /path_to/file.ffs_batch --display=:0.0

The error "Unable to initialize GTK +, is DISPLAY set properly?" it is produced by not defining who executes the task, therefore this must be specified:

sudo crontab -e
# or
crontab -e

You must also specify the hour / minute / second / day / week / month when the task will be executed. Example:

0 10 * * * export DISPLAY=:0; /path_to/FreeFileSync /path_to/task.ffs_batch
# or
@weekly export DISPLAY=:0; /path_to/FreeFileSync /path_to/task.ffs_batch

Source: Mirror synchronization


You need to use 1-59 instead of * in your cron job

1 10 * * * /home/yzT/BackupDaily.sh
  • can you edit your post with the place to put 1-59 ? On a side note, I am not sure this answer the question.
    – Archemar
    Oct 20, 2015 at 9:55
  • @yzT another way, make a log record for you cron task. 0 10 * * * /home/yzT/BackupDaily.sh >> /tmp/cron.log 2>&1
    – Fred
    Oct 20, 2015 at 9:58
  • 1
    0 is perfectly valid for any of these fields.
    – Bram
    Oct 20, 2015 at 10:39
  • This answer is wrong on so many levels... "instead of *" and then you replace the 0, not the *. And * and 0 are valid, as Bram pointed out
    – wurtel
    Oct 20, 2015 at 13:01

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