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Full Discussion: SED command explanation
Top Forums UNIX for Dummies Questions & Answers SED command explanation Post 302433258 by Scrutinizer on Tuesday 29th of June 2010 05:28:19 AM
Old 06-29-2010
It looks for at least one character that is not a '|' ( [^|] ) at the start of the line plus the first '|' and stores it in variable 1 it stores the rest of the line in variable 2. Then it prints variable 2 followed by variable 1 ( \2\1 ). IMO in practice it is equivalent to:
Code:
sed 's/\([^|]*|\)\(.*\)/\2\1/'


Last edited by Scrutinizer; 06-29-2010 at 06:37 AM..
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SHTOOL-SUBST.TMP(1)					      GNU Portable Shell Tool					       SHTOOL-SUBST.TMP(1)

NAME
shtool-subst - GNU shtool sed(1) substitution operations SYNOPSIS
shtool subst [-v|--verbose] [-t|--trace] [-n|--nop] [-w|--warning] [-q|--quiet] [-s|--stealth] [-i|--interactive] [-b|--backup ext] [-e|--exec cmd] [-f|--file cmd-file] [file] [file ...] DESCRIPTION
This command applies one or more sed(1) substitution operations to stdin or any number of files. OPTIONS
The following command line options are available. -v, --verbose Display some processing information. -t, --trace Enable the output of the essential shell commands which are executed. -n, --nop No operation mode. Actual execution of the essential shell commands which would be executed is suppressed. -w, --warning Show warning on substitution operation resulting in no content change on every file. The default is to show a warning on substitution operations resulted in no content change on all files. -q, --quiet Suppress warning on substitution operation resulting in no content change. -s, --stealth Stealth operation. Preserve timestamp on file. -i, --interactive Enter interactive mode where the user has to approve each operation. -b, --backup ext Preserve backup of original file using file name extension ext. Default is to overwrite the original file. -e, --exec cmd Specify sed(1) command directly. -f, --file cmd-file Read sed(1) command from file. EXAMPLE
# shell script shtool subst -i -e 's;(c) ([0-9]*)-2000;(c) 1-2001;' *.[ch] # RPM spec-file %install shtool subst -v -n -e 's;^(prefix=).*;1 $RPM_BUILD_ROOT%{_prefix};g' -e 's;^(sysconfdir=).*;1 $RPM_BUILD_ROOT%{_prefix}/etc;g' `find . -name Makefile -print` make install HISTORY
The GNU shtool subst command was originally written by Ralf S. Engelschall <rse@engelschall.com> in 2001 for GNU shtool. It was prompted by the need to have a uniform and convenient patching frontend to sed(1) operations in the OpenPKG package specifications. SEE ALSO
shtool(1), sed(1). 18-Jul-2008 shtool 2.0.8 SHTOOL-SUBST.TMP(1)
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