Linux command to find and replace occurance of more than two equal sign with "==" from XML file. Post: 302661083

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Operating Systems Linux Linux command to find and replace occurance of more than two equal sign with "==" from XML file. Post 302661083 by bakunin on Sunday 24th of June 2012 05:44:54 PM

06-24-2012

Registered User

Quote:

Originally Posted by RedRocks!!

Thank you for your suggestion. I have used, Below command, where it gives output in same file.

You seem to have misunderstood what i explained. "perl -i" does the same as "sed -i": it creates a temporary second file where it stores the changes and moves this over the original file as the last step.

You gain nothing by using perl (save for a considerably slower speed of execution, because native UNIX commands are way faster).

The point is simple: to edit a file you need to be able to store 2 versions of it.*) There is no way around that. The "-i" options of various tools just blur that fact by hiding this temporary file, but it is still necessary.

If you fear a long execution time for moving the file: don't. It is in fact just a change in the files i-node (which is a few bytes) as long as the temporary file and the original file are on the same filesystem. To execute

Code:

mv /path/to/fileA /path/to/fileB

takes the same time, regardless of the size of this file (as long as they both are on the same filesystem). So set your "TMP" or "TMPDIR" variable accordingly and have enough room on your disk - some 100GB should not really be a problem these times of multi-TB SAN storage fabrics.

I hope this helps.

bakunin

________________

*) actually this is not completely true, because there is a trick:

Code:

(cat /path/to/file) | sed '<somecommand>' > /path/to/file

This will work for files which are small enough to fit into memory. The downside is, that if anything goes wrong (power loss, reboot, process aborted, ...) your data will be irrevocably destroyed. You sure do not want to use this hack on critical data just to save a few GB of (temporary) diskspace.

Last edited by bakunin; 06-24-2012 at 06:51 PM..

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shtool-install

SHTOOL-INSTALL.TMP(1)					      GNU Portable Shell Tool					     SHTOOL-INSTALL.TMP(1)

NAME

       shtool-install - GNU shtool install(1) command

SYNOPSIS

       shtool install [-v|--verbose] [-t|--trace] [-d|--mkdir] [-c|--copy] [-C|--compare-copy] [-s|--strip] [-m|--mode mode] [-o|--owner owner]
       [-g|--group group] [-e|--exec sed-cmd] file [file ...]  path

DESCRIPTION

       This command installs a one or more files to a given target path providing all important options of the BSD install(1) command.	The trick
       is that the functionality is provided in a portable way.

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.

       -d, --mkdir
	   To maximize BSD compatiblity, the BSD "shtool "install -d"" usage is internally mapped to the "shtool "mkdir -f -p -m 755"" command.

       -c, --copy
	   Copy the file to the target path. Default is to move.

       -C, --compare-copy
	   Same as -c except if the destination file already exists and is identical to the source file, no installation is done and the target
	   remains untouched.

       -s, --strip
	   This option strips program executables during the installation, see strip(1). Default is to install verbatim.

       -m, --mode mode
	   The file mode applied to the target, see chmod(1). Setting mode to ""-"" skips this step and leaves the operating system default which
	   is usually based on umask(1). Some file modes require superuser privileges to be set. Default is 0755.

       -o, --owner owner
	   The file owner name or id applied to the target, see chown(1). This option requires superuser privileges to execute. Default is to skip
	   this step and leave the operating system default which is usually based on the executing uid or the parent setuid directory.

       -g, --group group
	   The file group name or id applied to the target, see chgrp(1). This option requires superuser privileges to execute to the fullest
	   extend, otherwise the choice of group is limited on most operating systems.	Default is to skip this step and leave the operating
	   system default which is usually based on the executing gid or the parent setgid directory.

       -e, --exec sed-cmd
	   This option can be used one or multiple times to apply one or more sed(1) commands to the file contents during installation.

EXAMPLE

	#   Makefile
	install:
	     :
	    shtool install -c -s -m 4755 foo $(bindir)/
	    shtool install -c -m 644 foo.man $(mandir)/man1/foo.1
	    shtool install -c -m 644 -e "s/@p@/$prefix/g" foo.conf $(etcdir)/

HISTORY

       The GNU shtool install command was originally written by Ralf S.  Engelschall <rse@engelschall.com> in 1997 for GNU shtool. It was prompted
       by portability issues in the installation procedures of OSSP libraries.

SEE ALSO

       shtool(1), umask(1), chmod(1), chown(1), chgrp(1), strip(1), sed(1).

18-Jul-2008							   shtool 2.0.8 					     SHTOOL-INSTALL.TMP(1)