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Full Discussion: sed / grep / for statement performance - please help
Top Forums Shell Programming and Scripting sed / grep / for statement performance - please help Post 302368362 by TonyFullerMalv on Wednesday 4th of November 2009 04:54:49 PM
Old 11-04-2009
I suspect that:
Code:
if [ -z "`grep $1 debug.files`" ] ; then

will be quicker than:
Code:
S=`grep $1 debug.files`
if [ "$S" = "" ] ; then

Also:
Code:
awk '{print $1}' "$FILE1" |

will be more efficient than:
Code:
cat "$FILE1" | awk '{print $1}' |

But if you are really serious about performance then using perl(1) would be quicker, that is using one binary to do all the processing rather than calling: grep(1), test(1), sed(1), etc.

Saying that I know some very able folk who could do the whole thing in nawk(1)!

Hope this helps...
 

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LEARN ABOUT X11R4

zgrep

ZGREP(1)                                                      General Commands Manual                                                     ZGREP(1)

NAME

       zgrep - search possibly compressed files for a regular expression

SYNOPSIS

       zgrep [ grep_options ] [ -e ] pattern filename...

DESCRIPTION

       Zgrep  invokes  grep  on  compressed  or  gzipped  files.   These  grep  options  will  cause  zgrep  to  terminate  with  an  error  code:
       (-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*).  All other options specified are passed directly to grep.  If no file is specified,  then  the
       standard input is decompressed if necessary and fed to grep.  Otherwise the given files are uncompressed if necessary and fed to grep.

       If the GREP environment variable is set, zgrep uses it as the grep program to be invoked.

EXIT CODE

       2 - An option that is not supported was specified.

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

       grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)

                                                                                                                                          ZGREP(1)
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