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Top Forums Shell Programming and Scripting Bash syntax behaviour : [[ vs [ Post 302880991 by Scrutinizer on Wednesday 25th of December 2013 04:57:49 PM
Old 12-25-2013
In the case of single brackets, pathname expansion does get performed, however in the case of double brackets this is not the case, so in your example with single brackets after variable expansion of $RESTORE_FF.* to a_file.tar.gz.*, the pathname pattern gets expanded to a_file.tar.gz., so it would look for the literal file a_file.tar.gz. and in the case of double brackets for the literal file a_file.tar.gz.*, which does not exist. The example with single brackets will give a syntax error if more than one file with the given pattern exists.

Last edited by Scrutinizer; 12-25-2013 at 06:15 PM..
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PTARGREP(1)						 Perl Programmers Reference Guide					       PTARGREP(1)

NAME
ptargrep - Apply pattern matching to the contents of files in a tar archive SYNOPSIS
ptargrep [options] <pattern> <tar file> ... Options: --basename|-b ignore directory paths from archive --ignore-case|-i do case-insensitive pattern matching --list-only|-l list matching filenames rather than extracting matches --verbose|-v write debugging message to STDERR --help|-? detailed help message DESCRIPTION
This utility allows you to apply pattern matching to the contents of files contained in a tar archive. You might use this to identify all files in an archive which contain lines matching the specified pattern and either print out the pathnames or extract the files. The pattern will be used as a Perl regular expression (as opposed to a simple grep regex). Multiple tar archive filenames can be specified - they will each be processed in turn. OPTIONS
--basename (alias -b) When matching files are extracted, ignore the directory path from the archive and write to the current directory using the basename of the file from the archive. Beware: if two matching files in the archive have the same basename, the second file extracted will overwrite the first. --ignore-case (alias -i) Make pattern matching case-insensitive. --list-only (alias -l) Print the pathname of each matching file from the archive to STDOUT. Without this option, the default behaviour is to extract each matching file. --verbose (alias -v) Log debugging info to STDERR. --help (alias -?) Display this documentation. COPYRIGHT
Copyright 2010 Grant McLean <grantm@cpan.org> This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.18.2 2018-08-17 PTARGREP(1)
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