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Top Forums Shell Programming and Scripting standard error to standard out question Post 302318787 by pludi on Friday 22nd of May 2009 08:46:12 AM
Old 05-22-2009
Even if it would mean changing some of your script, I don't think that it would be too much in relation to gained stability and maintainability, eg if your previous code was
Code:
zfs list | grep fred >/dev/null 2>&1
if [ $? -ne 0 ]...

a change would be as simple as
Code:
if [ -x /path/to/zfs ]
then
    zfs list | grep fred >/dev/null 2>&1
    zfs_found=$?
else
    zfs_found=1
fi
if [ $zfs_found -ne 0 ]...

If, however, you are absolutely sure that there is no other way, at the top of your script put the line
Code:
exec 2>/dev/null

which will redirect all stderr messages to /dev/null (even those that might indicate a serious problem)

Last edited by pludi; 05-22-2009 at 09:57 AM.. Reason: Code example
 

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GREP(1) 						      General Commands Manual							   GREP(1)

NAME
grep - search a file for a pattern SYNOPSIS
grep [ option ... ] pattern [ file ... ] DESCRIPTION
Grep searches the input files (standard input default) for lines (with newlines excluded) that match the pattern, a regular expression as defined in regexp(6). Normally, each line matching the pattern is `selected', and each selected line is copied to the standard output. The options are -c Print only a count of matching lines. -h Do not print file name tags (headers) with output lines. -i Ignore alphabetic case distinctions. The implementation folds into lower case all letters in the pattern and input before interpre- tation. Matched lines are printed in their original form. -l (ell) Print the names of files with selected lines; don't print the lines. -L Print the names of files with no selected lines; the converse of -l. -n Mark each printed line with its line number counted in its file. -s Produce no output, but return status. -v Reverse: print lines that do not match the pattern. Output lines are tagged by file name when there is more than one input file. (To force this tagging, include /dev/null as a file name argument.) Care should be taken when using the shell metacharacters $*[^|()= and newline in pattern; it is safest to enclose the entire expression in single quotes '...'. SOURCE
/sys/src/cmd/grep.c SEE ALSO
ed(1), awk(1), sed(1), sam(1), regexp(6) DIAGNOSTICS
Exit status is null if any lines are selected, or non-null when no lines are selected or an error occurs. GREP(1)
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