Expression (if,while) get command exit code '{ }' to support redirection to /dev/null or no output at all

[c-pointer]

I don't know if it is bug or enhancement but

This works

if ( { ping -c 1 -w 1 192.168.0.1 } ) then
  echo "LAN is up"
endif

This does not works (works but redirection does not)

if ( { ping -c 1 -w 1 192.168.0.1 >& /dev/null } ) then
  echo "LAN is up"
endif

[suominen]

Alternative approaches:

ping -c 1 -w 1 192.168.0.1 >& /dev/null && echo "LAN is up"

or

ping -c 1 -w 1 192.168.0.1 >& /dev/null
if ( $? == 0 ) then
  echo "LAN is up"
endif

[zoulasc]

Should be fixed now. christos

…

On Nov 4, 2024, at 5:16 AM, Kimmo Suominen ***@***.***> wrote: Alternative approaches: ping -c 1 -w 1 192.168.0.1 >& /dev/null && echo "LAN is up" or ping -c 1 -w 1 192.168.0.1 >& /dev/null if ( $? == 0 ) then echo "LAN is up" endif — Reply to this email directly, view it on GitHub <#113 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAENP5PH7NYUAZPY5RQWK2TZ65COHAVCNFSM6AAAAABRCYWVZSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDINJUGMYTANRZHE>. You are receiving this because you are subscribed to this thread. <sanitizer.log>

[Krush206]

I tested the fix some months ago, @zoulasc. There still seems to be a problem remaining there, which I can't recall now. Anyhow, here's my fix. Commands are re-parsed in expressions.

[Krush206]

This has always been a bug in tcsh and csh, @c-pointer. The best solution I can provide is to fork into a FIFO file. Better yet, redirect the file descriptors present in the file system. Christos' solution seems to work for redirections, though not for pipes. My provided solution fixes pipes, too.

Note tcsh and csh are indirect forks of PWB and V6 shells. Either shells share the same issues.