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Full Discussion: Variable expansion in sed
Top Forums Shell Programming and Scripting Variable expansion in sed Post 302497175 by alister on Wednesday 16th of February 2011 02:06:04 PM
Old 02-16-2011
As has been mentioned, you could use a different regular expression delimiter, a character that you know will never appear in the pathname.

Instead of
Code:
sed "s/^.*/grep &/g"

you can use
Code:
sed "s@^.*@grep &@g"

if the at symbol will never be used.

That said, interpolating values like that is fragile when the tool does not support some form of quoting to strip special meaning from metacharacters (at least in this case it's in the replacement text, otherwise you'd have more special characters to worry about if the parameter expansion were ocurring in the regular expression section of the sed command. Even so, ampersand is still special in this context, though admittedly not very likely to appear in a pathname.).

To be safe, to simplify, and to minimize stress, I would tend to prefer something that avoids interpolating into special contexts as much as possible. Possible alternatives:

Code:
awk -F\| -v aname="$ARCHIVENAME" {print "grep " $1 " \"" aname "\"/clean_*" > (aname"/create_message_names")}'

or
Code:
while IFS=\| read -r pattern junk; do
    printf 'grep %s "%s"/clean_*\n' "$pattern" "$ARCHIVENAME" > "$ARCHIVENAME"/create_message_name
done

Regards,
Alister
Last edited by alister; 02-16-2011 at 03:35 PM..
 

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LEARN ABOUT LINUX

shtool-subst

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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