I'm writing a shell script for Mac OS/Linux. The script is run by a cron job. I'm trying to append stdout and stderr to a log file. My command(simplified) looks like this(line 5 in myscript.sh):

mycommand &>> log.txt

I get the following error:

myscript.sh: line 5: syntax error near unexpected token `>

However if I change the command to:

mycommand &> log.txt

I don't get any errors, but the file is overwritten (not appended).

Any idea why &>> doesn't work but &> works?

  • @KamilMaciorowski the command I showed is in line 5 in myscript.sh – Caner Apr 11 '18 at 12:16

cron is executed using sh and the redirection syntax you are attempting to use is a Bash extension (and a fairly recent one at that; older versions of Bash only supported &>).

The portable way to append standard output and standard error to a file is

mycommand >>log.txt 2>&1
  • excellent, this works and also explains the behaviour! – Caner Apr 11 '18 at 12:24

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