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Full Discussion: double quotes
Top Forums Shell Programming and Scripting double quotes Post 302228947 by bakunin on Monday 25th of August 2008 10:08:19 PM
Old 08-25-2008
sed 's/""/"/'

If it doesn't exactly what you want twiddle yourself with it. Here is how to do it:

The s-command (s is for substitute) is a simple sed-device:

s/<pattern>/<new>/

will change every first occurence of <pattern> in a line with <new>. For example:

s/dog/cat/

will change the first occurrence of the word "dog" on every line to the word "cat".

Code:
Source Text

This is a dog.
One dog chases another dog.

Result Text

This is a cat.
One cat chases another dog.

Notice that only the first occurrence is changed, hence the second "dog" still stands there. If you want every occurrence to be changed use the "g" option for the s-command:

s/dog/cat/g

This would change the second (and any other) occurrence in the second line too.

sed and awk are mighty tools and you should put much effort in learning them when you work in a Unix environment. I recommend Dale Doughertys book "sed & awk" (O'Reilly) as simply the best book i know on this topic.

I hope this helps.

bakunin
 

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PCRESAMPLE(3)						     Library Functions Manual						     PCRESAMPLE(3)

NAME
PCRE - Perl-compatible regular expressions PCRE SAMPLE PROGRAM
A simple, complete demonstration program, to get you started with using PCRE, is supplied in the file pcredemo.c in the PCRE distribution. The program compiles the regular expression that is its first argument, and matches it against the subject string in its second argument. No PCRE options are set, and default character tables are used. If matching succeeds, the program outputs the portion of the subject that matched, together with the contents of any captured substrings. If the -g option is given on the command line, the program then goes on to check for further matches of the same regular expression in the same subject string. The logic is a little bit tricky because of the possibility of matching an empty string. Comments in the code explain what is going on. If PCRE is installed in the standard include and library directories for your system, you should be able to compile the demonstration pro- gram using this command: gcc -o pcredemo pcredemo.c -lpcre If PCRE is installed elsewhere, you may need to add additional options to the command line. For example, on a Unix-like system that has PCRE installed in /usr/local, you can compile the demonstration program using a command like this: gcc -o pcredemo -I/usr/local/include pcredemo.c -L/usr/local/lib -lpcre Once you have compiled the demonstration program, you can run simple tests like this: ./pcredemo 'cat|dog' 'the cat sat on the mat' ./pcredemo -g 'cat|dog' 'the dog sat on the cat' Note that there is a much more comprehensive test program, called pcretest, which supports many more facilities for testing regular expres- sions and the PCRE library. The pcredemo program is provided as a simple coding example. On some operating systems (e.g. Solaris), when PCRE is not installed in the standard library directory, you may get an error like this when you try to run pcredemo: ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory This is caused by the way shared library support works on those systems. You need to add -R/usr/local/lib (for example) to the compile command to get round this problem. AUTHOR
Philip Hazel University Computing Service Cambridge CB2 3QH, England. REVISION
Last updated: 23 January 2008 Copyright (c) 1997-2008 University of Cambridge. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWpcre | +--------------------+-----------------+ |Interface Stability | Uncommitted | +--------------------+-----------------+ NOTES
Source for PCRE is available on http://opensolaris.org. PCRESAMPLE(3)
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