While loops and awk Post: 87637

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Top Forums Shell Programming and Scripting While loops and awk Post 87637 by Loriel on Wednesday 26th of October 2005 12:01:49 PM

10-26-2005

Registered User

While loops and awk

I am trying to make a script that will replace backslashes in a file, but only if the occurance is a pathname. In the file, there are a lot of regular expressions as well, so I'm trying to preserve the integrity of those regular expressions, but convert Windows relative paths. I'm using bash and this is what I've tried:

line="~/path/to/something~ ~\path\to\something~"
loop=2
while [ ! "`echo \"$oldline\" | grep '\\\'`" ]; do # see note...
oldline="`echo \"$line\" | tr -d '\r' | awk -F \~ '{print $loop}'`"
let loop=$loop+2
done

Note: I'm using Mac OS X and apparently Darwin doesn't like a simple escaped backslash. I have to escape the escaping backslash to get it to work. Just don't try to match multiple backslashes, 'cause then it's even more crazy. Just a side note...

I've tried these variants of the $loop variable in the awk statement:
awk -F \~ '{print $loop}'
awk -F \~ '{print $$loop}'
awk -F \~ '{print \$$loop}'
awk -F \~ '{print $\$loop}'
awk -F \~ '{print $"$loop"}'

Of course, they all lead to the same error - illegal field $loop. Can anyone help me with an alternate way of doing this?

Loriel

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LEARN ABOUT ULTRIX

regex

regex(3)						     Library Functions Manual							  regex(3)

Name
       re_comp, re_exec - regular expression handler

Syntax
       char *re_comp(s)
       char *s;

       re_exec(s)
       char *s;

Description
       The  subroutine	compiles  a string into an internal form suitable for pattern matching.  The subroutine checks the argument string against
       the last string passed to

       The subroutine returns 0 if the string s was compiled successfully; otherwise a string containing an  error  message  is  returned.  If	is
       passed 0 or a null string, it returns without changing the currently compiled regular expression.

       The  subroutine returns 1 if the string s matches the last compiled regular expression, 0 if the string s failed to match the last compiled
       regular expression, and -1 if the compiled regular expression was invalid (indicating an internal error).

       The strings passed to both and may have trailing or embedded newline characters; they are terminated by	nulls.	 The  regular  expressions
       recognized are described in the manual entry for given the above difference.

Diagnostics
       The subroutine returns -1 for an internal error.

       The subroutine returns one of the following strings if an error occurs:

       No previous regular expression
       Regular expression too long
       unmatched (
       missing ]
       too many () pairs
       unmatched )

See Also
       ed(1), ex(1), egrep(1), fgrep(1), grep(1)

																	  regex(3)

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