Linux – Redirect cronjob STDOUT and STDERR to /dev/null not working

cronlinuxredirectstderrstdout

I'm baffled as to why this isn't working.

I've tried redirecting STDOUT and STDERR using "&>" and also "2>&1" and neither seems to work. I still get e-mailed by this cron job (every minute!) with smbclient complaining that there are no files in the share.

* * * * * smbclient //scanner/scan-import secretpass -U administrator -c "prompt; mget *; del *" &> /dev/null

For the curious: A client has an old and expensive scanner that scans multiple documents at high speed–but the software has no way to configure the save location. They don't want the documents saved directly on the old XP workstation, so I've shared out the save location and use this cron job to automatically pull the documents over to their linux server.

Best Answer

Bash supports redirecting stdout and stdin together using &>, but sh does not. Cron used the Bourne shell (sh) rather than Bash. Use >/dev/null 2>&1 instead.

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Ftp – How to capture output from LFTP? (Output not written to STDOUT or STDERR?)

It sounds to me like it's buffering its output. You might try the unbuffer expect script (man page).

Linux – Redirect output of Python program to /dev/null

The program may be writing to the tty instead of stdout. You may be able to use the unbuffer script that comes with expect or some other technique using expect or something similar.

Here's a demonstration. Create this script and call it "writetty". Then do chmod u+x writetty:

#!/bin/bash
date > /dev/tty

Now try it out:

$ ./writetty
Tue Jun  8 12:24:36 CDT 2010
$ ./writetty > /dev/null
Tue Jun  8 12:24:46 CDT 2010
$ var=$(./writetty)
Tue Jun  8 12:24:56 CDT 2010
$ unbuffer ./writetty > /tmp/writetty.out
$ cat /tmp/writetty.out
Tue Jun  8 12:25:06 CDT 2010
$ var=$(unbuffer ./writetty)
$ echo $var
Tue Jun  8 12:25:16 CDT 2010

You could use expect to respond to the program's request for input instead of killing it.

Best Answer

Related Solutions

Ftp – How to capture output from LFTP? (Output not written to STDOUT or STDERR?)

Linux – Redirect output of Python program to /dev/null

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