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Top Forums Shell Programming and Scripting Bash syntax behaviour : [[ vs [ Post 302881093 by jcdole on Thursday 26th of December 2013 01:59:33 PM
Old 12-26-2013
[SOLVED] Bash syntax behaviour : [[ vs [

Quote:
Originally Posted by Scrutinizer
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.
Thank you very much.

Last edited by jcdole; 12-26-2013 at 03:04 PM..
 

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tar(4)							     Kernel Interfaces Manual							    tar(4)

NAME
tar - format of tar tape archive DESCRIPTION
The header structure produced by (see tar(1)) is as follows (the array size defined by the constants is shown on the right): All characters are represented in ASCII. There is no padding used in the header block; all fields are contiguous. The fields magic, uname, and gname are null-terminated character strings. The fields name, linkname, and prefix are null-terminated char- acter strings except when all characters in the array contain non-null characters, including the last character. The version field is two bytes containing the characters (zero-zero). The typeflag contains a single character. All other fields are leading-zero-filled octal numbers in ASCII. Each numeric field is terminated by one or more space or null characters. The name and the prefix fields produce the pathname of the file. The hierarchical relationship of the file is retained by specifying the pathname as a path prefix, with a slash character and filename as the suffix. If the prefix contains non-null characters, prefix, a slash character, and name are concatenated without modification or addition of new characters to produce a new pathname. In this manner, path- names of at most 256 characters can be supported. If a pathname does not fit in the space provided, the format-creating utility notifies the user of the error, and no attempt is made to store any part of the file, header, or data on the medium. SEE ALSO
tar(1) STANDARDS CONFORMANCE
tar(4)
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