Redirect stderr to stdout in C shell

Question

When I run the following command in csh  I got nothing  but it works in bash  Is there any equivalent in csh which can redirect the standard error to standard out   somecommand 2 gt  amp 1

User · Answer

I think this is the correct answer for csh.

xxx >/dev/stderr

Note most csh are really tcsh in modern environments:

rmockler> ls -latr /usr/bin/csh

lrwxrwxrwx 1 root root 9 2011-05-03 13:40 /usr/bin/csh -> /bin/tcsh

using a backtick embedded statement to portray this as follows:

echo "`echo 'standard out1'` `echo 'error out1' >/dev/stderr` `echo 'standard out2'`" | tee -a /tmp/test.txt ; cat /tmp/test.txt

if this works for you please bump up to 1. The other suggestions don't work for my csh environment.

User · Answer

The csh shell has never been known for its extensive ability to manipulate file handles in the redirection process   You can redirect both standard output and error to a file with   xxx  gt  amp  filename   but that s not quite what you were after  redirecting standard error to the current standard output     However  if your underlying operating system exposes the standard output of a process in the file system  as Linux does with  dev stdout   you can use that method as follows   xxx  gt  amp   dev stdout   This will force both standard output and standard error to go to the same place as the current standard output  effectively what you have with the bash redirection  2 gt  amp 1   Just keep in mind this isn t a csh feature  If you run on an operating system that doesn t expose standard output as a file  you can t use this method     However  there is another method  You can combine the two streams into one if you send it to a pipeline with   amp   then all you need to do is find a pipeline component that writes its standard input to its standard output  In case you re unaware of such a thing  that s exactly what cat does if you don t give it any arguments  Hence  you can achieve your ends in this specific case with   xxx   amp  cat     Of course  there s also nothing stopping you from running bash  assuming it s on the system somewhere  within a csh script to give you the added capabilities  Then you can use the rich redirections of that shell for the more complex cases where csh may struggle   Let s explore this in more detail  First  create an executable echo err that will write a string to stderr    include  lt stdio h gt  int main  int argc  char  argv          fprintf  stderr   stderr   s  n    argc  gt  1    argv 1              return 0      Then a control script test csh which will show it in action      usr bin csh  ps -ef   echo   echo      echo  echo  stdout  csh     echo err csh  bash -c    echo  stdout  bash       echo err bash   2 gt  amp 1    The echo of the PID and ps are simply so you can ensure it s csh running this script  When you run this script with     test csh  gt test out 2 gt test err    the initial redirection is set up by bash before csh starts running the script   and examine the out err files  you see   test out      UID     PID    PPID  TTY        STIME     COMMAND     pax    5708    5364  cons0      11 31 14   usr bin ps     pax    5364    7364  cons0      11 31 13   usr bin tcsh     pax    7364       1  cons0      10 44 30   usr bin bash      5364      stdout  csh      stdout  bash      stderr  bash   test err      stderr  csh    You can see there that the test csh process is running in the C shell  and that calling bash from within there gives you the full bash power of redirection   The 2 gt  amp 1 in the bash command quite easily lets you redirect standard error to the current standard output  as desired  without prior knowledge of where standard output is currently going

User · Answer

As paxdiablo said you can use  gt  amp  to redirect both stdout and stderr   However if you want them separated you can use the following    command  gt  stdoutfile   gt  amp  stderrfile      as indicated the above will redirect stdout to stdoutfile and stderr to stderrfile

User · Answer

I object the above answer and provide my own  csh DOES have this capability and here is how it s done   xxx   amp  some exec   will pipe merged output to your some exec    or   xxx   amp  cat  gt  filename   or if you just want it to merge streams  to stdout  and not redirect to a file or some exec   xxx   amp  tee  dev null

User · Answer

What about just   xxx  gt  amp   dev stdout

User · Answer

xxx  gt  amp  filename   Or do this to see everything on the screen and have it go to your file     xxx    amp  tee   logfile

[io-redirection] Redirect stderr to stdout in C shell

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