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Full Discussion: Insert a line in a text file
Top Forums Shell Programming and Scripting Insert a line in a text file Post 302220559 by bakunin on Friday 1st of August 2008 05:56:16 AM
Old 08-01-2008
Quote:
Originally Posted by 4scriptmoni
I like the sed one more, its just less complicated command.
Good guy! ;-))


Quote:
But both output to the screen I need it to write to that same file.
I tried

[...]

Is that the best way ?
Yes, more or less. sed principally does not overwrite the file it works on, so you have to save its results to a temporary file and copy/move the contents over the original afterwards. You can use "mv" instead of "cp", because you don't need a save copy of the results file, but thats a minor issue:

mv (instead of cp) new.txt servicegroup-24x7-comm.cfg

Quote:
Also I need to pass a variable to that command how do it do??
[...]
that prints $LINEX
The reason is, that sed commands might contain characters which have special meaning to the shell. To prevent the shell from being confused we usually surround all sed programs with single quotes, which do exactly this:

sed 'some_commands' file > file.new

Unfortunately this also prevents the special character "$" to be interpreted: An expression like "$variable" is in fact a command to the shell, saying: replace the string "$variable" with the content of the variable "variable". After preventing this interpretation this mechanism doesn't work any more, which is why you get the result "$LINEX" instead of the content of the variable LINEX. Therefore the solution is to find a way to exclude the variable expression from the single-quoted string:

sed '/alias 24x7-comunicacions/a\'"$LINEX" $FILECFG

I hope this helps.

bakunin
 

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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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