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Full Discussion: When does an if statement need parentheses
Top Forums Shell Programming and Scripting When does an if statement need parentheses Post 302546072 by DGPickett on Wednesday 10th of August 2011 10:22:19 AM
Old 08-10-2011
Shell if with no parens takes a single command execution string, possibly piped and subshell'd (), and a $? of 0 is true, like "if grep -q haha logfile ; then . . . ." The $? is from the last command, as I recall, so "if find . -type f|grep -q .profile ; then . . . ." tests the exit() value of grep and "if ( find . -type f >/tmp/myfiles ; grep -q .profile /tmp/myfiles ); then . . . ." also tests grep. (An extra fork() and named file open twice is probably more expensive than a pipe() call, slower because of latency and leaves a file behind.)
 

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LEARN ABOUT MINIX

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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