Illegal option -f in my shell script

[willsch89]

Hi

I get this error: "Illegal option -f" in my shell script
only when I run with watch command: watch -n 4 ./collect-results.sh

When I use only ./collect-results.sh works fine

Any ideas?

#/bin/bash
...


export -f get_data
export -f get_jitter
export -f get_average_throughput
export -f get_total_latency
export -f get_maximum_latency

Thanks

[steeldriver]

Hello and welcome to the forum

I suspect it's because watch is running the command in a dash shell - overriding your #!/bin/bash shebang - from the watch manpage

NOTE
       Note that command is given to "sh -c" which means that you may need to
       use extra quoting to get the desired effect.  You can disable this with
       the -x or --exec option, which passes the command to exec(2) instead.

(in Ubuntu, /bin/sh is a symlink to /bin/dash by default). There doesn't seem to be an explicit option to tell it to use bash - if it's essential to make this work, you could always modify the symlink (I've done that myself, for things that really won't work otherwise - e.g. Makefiles that assume /bin/sh is a bash shell).