Why does bash sometimes say `Broken pipe'?

Why does bash sometimes say `Broken pipe'? 


If a sequence of commands appears in a pipeline, and one of the

reading commands finishes before the writer has finished, the

writer receives a SIGPIPE signal.  Many other shells special-case

SIGPIPE as an exit status in the pipeline and do not report it. 

For example, in:

  

      ps -aux | head

  

`head' can finish before `ps' writes all of its output, and ps

will try to write on a pipe without a reader.  In that case, bash

will print `Broken pipe' to stderr when ps is killed by a

SIGPIPE. 



You can build a version of bash that will not report SIGPIPE errors

by uncommenting the definition of DONT_REPORT_SIGPIPE in the file

config-top.h.

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