Ölbaum’s Delirium

A quick reference to pipes and redirections in tcsh.

Pipes

• Use the standard output of program_1 as the standard input of program_2:

  program_1 | program_2
  

• Use the standard and diagnostic outputs of program_1 as the standard input of program_2:

  program_1 |& program_2
  

Redirections

• Open file name as the standard input:

  program < name
  

• Use file name as the standard output:

  program > name
  

• Append the output to the end of file name:

  program >> name
  

• Route both the standard and diagnostic outputs to file name:

  program >& name
  

• Append both the standard and diagnostic outputs to file name:

  program >>& name
  

Tips

• To route the standard and diagnostic outputs to separate files, use the following syntax:

  ( program > outfile ) >& errfile
  

• To route the diagnostic output to a file and the standard output to the terminal, use:

  ( program > /dev/tty ) >& errfile
  

• To retain only the diagnostic output, redirect the standard output to /dev/null:

  program > /dev/null
  ( program > /dev/null ) >& errfile
  

• In order to test pipes and redirections, use the following Perl program:

  #!/usr/bin/perl
  
  
  print STDOUT "STDOUT: Standard output\n";
  print STDERR "STDERR: Diagnostic output\n";
  

# Posted by Ölbaum, late morning | Comments (3) | TrackBacks (0)

I have decided to move my knowledge base to my main blog. The benefits are threefold:

• I can repost knowledge base articles and give the impression that I update my blog more often;
• Since I post other things here, it becomes less visible that I very rarely update the knowledge base;
• I save one blog for when I upgrade to Movable Type 3

I will start moving the articles right now, starting with the most popular one: Pipes and redirections in tcsh. Of course, the old knowledge base permalinks will still work, long live mod_rewrite.

# Posted by Ölbaum, late morning | Comments (0) | TrackBacks (0)