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Full Discussion: Using AWK in a for loop
Top Forums Shell Programming and Scripting Using AWK in a for loop Post 302347292 by Jahn on Tuesday 25th of August 2009 10:32:25 AM
Old 08-25-2009
Using AWK in a for loop
Hello,

I am trying to use AWK to print only the first field of numerous text files, and then overwrite these files. They are of the format 1*2,3,4,5. I have tried the following code (using tcsh):

Code:
 foreach f (file1 file2 file3)
cat $f | awk -F'*' '{print $1}' > $f
end

However, I get very inconsistent results each time I run this script. I have tried creating a tmp directory where I run the above command on a clean set of the files. But, sometimes it returns empty files, whereas other times it runs fine for all the files. Any ideas on what is going on here, or if there is a better way to get awk to do what I want?

On a side note, I have tried a similar method using cut:

Code:
 foreach f (file1 file2 file3)
cat $f | cut -d'*' -f1 > $f
end

but I get the same inconsistencies.


Thank you for your help,

-Jahn
 

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LEARN ABOUT OSF1

merge

merge(1)																  merge(1)

NAME

       merge - three-way file merge

SYNOPSIS

       merge [-Llabel1 [-Llabel3]] [-p] [-q] file1 file2 file3

DESCRIPTION

       merge  incorporates  all  changes that lead from file2 to file3 into file1. The result goes to standard output if -p is present, into file1
       otherwise.  merge is useful for combining separate changes to an original.  Suppose file2 is the original, and both  file1  and	file3  are
       modifications of file2. Then merge combines both changes.

       An  overlap occurs if both file1 and file3 have changes in a common segment of lines. On a few older hosts where diff3 does not support the
       -E option, merge does not detect overlaps, and merely supplies the changed lines from file3.  On most hosts, if overlaps occur, merge  out-
       puts a message (unless the -q option is given), and includes both alternatives in the result.  The alternatives are delimited as follows:

       <<<<<<< file1 lines in file1 ======= lines in file3 >>>>>>> file3

       If  there  are  overlaps,  the  user  should edit the result and delete one of the alternatives. If the -L label1 and -L label3 options are
       given, the labels are output in place of the names file1 and file3 in overlap reports.

DIAGNOSTICS

       Exit status is 0 for no overlaps, 1 for some overlaps, 2 for trouble.

IDENTIFICATION

       Author: Walter F. Tichy.
       Revision Number: 1.1.6.2; Release Date: 1993/10/07.
       Copyright (C) 1982, 1988, 1989 by Walter F. Tichy.
       Copyright (C) 1990, 1991 by Paul Eggert.

SEE ALSO

       diff3(1), diff(1), rcsmerge(1), co(1)

																	  merge(1)
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