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Top Forums Shell Programming and Scripting performance of shell script ( grep command) Post 302382381 by radoulov on Wednesday 23rd of December 2009 05:55:33 AM
Old 12-23-2009
Quote:
Originally Posted by steadyonabix
Is there a reason for only using xargs on one side of the pipe? I would have thought if there were too many arguments for the grep on the right the same would be true of the grep on the left, or is there some obscure reason I am missing? ( Wouldn't be the first time I am missing something... :-) )
The xargs here is not used to avoid the argument list too long error. I'm using it to pass the input as filename(s), not as STDIN.
Consider the following:
Code:
zsh-4.3.10[t]% print -l 1 2 > infile
zsh-4.3.10[t]% cat infile 
1
2
zsh-4.3.10[t]% grep -Fwl 1 infile | grep -Fwl 2
zsh-4.3.10[t]% grep -Fwl 1 infile | xargs grep -Fwl 2
infile

 

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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME
atf-sh [-s shell] -- interpreter for shell-based test programs SYNOPSIS
atf-sh script DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library. atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter- preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not use any non-standard extensions. The following options are available: -s shell Specifies the shell to use instead of the value provided by ATF_SHELL. ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes. ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes. ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a specific interpreter. EXAMPLES
Scripts using atf-sh(3) should start with: #! /usr/bin/env atf-sh Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode the path to atf-sh in the script and then use the -s option afterwards as a single parameter: #! /path/to/bin/atf-sh -s/bin/bash ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts. SEE ALSO
atf-sh(3) BSD
September 27, 2014 BSD
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