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Full Discussion: bash: How to reuse the search result of "find"
Top Forums Shell Programming and Scripting bash: How to reuse the search result of "find" Post 302609309 by LessNux on Monday 19th of March 2012 04:11:10 PM
Old 03-19-2012
If I need to use (or reuse) the search result later but not immediately following "find", I would like to save it into a variable. However, the search result contains null characters as separators, and bash removes null characters either upon variable assignment or upon variable expansion. To preserve null characters, the percent-encoding is useful.

Percent encoding is widely used for URL encoding. The following method applies percent-encoding to only the null character and the percent symbol itself.

Code:
#!/bin/bash
#percent-encoding for null character
PercentizeNull()
{
  sed "s/%/%25/g" | sed "s/\x0/%00/g"
}
DepercentizeNull()
{
  sed "s/%00/\x0/g" | sed "s/%25/%/g"
}
echo -ne "A\0B\0%\0" | hexdump -C
foo=$(echo -ne "A\0B\0%\0" | PercentizeNull)
printf %s "$foo" | DepercentizeNull | hexdump -C



The following example saves the search result of "find" into a variable with percent-encoding.

Code:
PercentizeNull()
{
  sed "s/%/%25/g" | sed "s/\x0/%00/g"
}
DepercentizeNull()
{
  sed "s/%00/\x0/g" | sed "s/%25/%/g"
}

vFound=$(find . -perm /o+rwx ! -type l -print0 2> /dev/null | PercentizeNull)

if test "$vFound" ; then
  echo "current permission"
  printf %s "$vFound" | DepercentizeNull | xargs -0 ls -ld
  printf %s "$vFound" | DepercentizeNull | xargs -0 chmod o-rwx
  echo "new permission"
  printf %s "$vFound" | DepercentizeNull | xargs -0 ls -ld
fi



By the way, does anyone know at which time bash removes null characters, at the time of variable assignment or at the time of variable expansion? Which time? Does bash never save null characters into a variable? Or, does bash save null characters into the variable, and does bash remove null characters when the variable is expanded?

Furthermore, without any encoding (such as percent encoding), is there any option to prevent bash from removing null characters?
Last edited by LessNux; 03-19-2012 at 05:28 PM..
 

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LEARN ABOUT SUSE

command-not-found

COMMAND-NOT-FOUND(1)					    http://en.opensuse.org/Sco					      COMMAND-NOT-FOUND(1)

NAME

       command-not-found - A command-not-found handler

SYNOPSIS

       command-not-found {binary_name} {repository}

ARGUMENTS

       The following arguments are required:

       binary_name
	   The name of binary you are looking for.

       repository
	   The name of repository for search. For most cases, use zypp

DESCRIPTION

       command-not-found handler is designed to tell users which package contains a missing command.

       The handler is integrated to bash(1) and zsh(1) shells and is not necessary to call it directly. Just type a name of the command in your
       favourite shell and you'll get a result.

       If you consider c-n-f handler useless, just add unset command_not_found_handle to your profile or remove the command-not-found package.

       Handler doesn't call the command-not-found binary directly, it only prints info about it. If you want to invoke it automatically, just add
       export COMMAND_NOT_FOUND_AUTO=1 to your bash profile.

EXAMPLE
: NORMAL USAGE
       For example you want to try blender, because you have heard that is an amazing program. So just type blender in shell:

	   $ blender

       You get the following output:

	   The program 'blender' can be found in the following package:
	     * blender [ path: /usr/bin/blender, repository: zypp (openSUSE 11.1-0) ]

	   Try installing with:
	       sudo zypper install blender

	   bash: blender: command not found

SEE ALSO

       scout(1)

AUTHOR

       Pavol Rusnak <stick@gk2.sk>
	   Developer

http://gitorious.org/opensus					    08/07/2009						      COMMAND-NOT-FOUND(1)
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