Multi platform script perl or awk


 
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Top Forums Shell Programming and Scripting Multi platform script perl or awk
# 1  
Old 10-02-2012
Multi platform script perl or awk

Hi gurus, I am trying to match records in following format:

Code:
(-,username,domain1.co.uk)\
(-,username,domain2.co.uk)

either awk or perl must be used. I am using cygwin. I wrote following code which works and matches both above entries:
Code:
awk 'BEGIN {musr="(-,username,[^)]+.co.uk)"} {if ($0~musr) print $0}' netgroup

But if I try to modify this regexp to be more specific the output is nothing:

# 1st: match record then last backslash and then match newline
Code:
"(-,username,[^)]+.co.uk)\\$"

# 2nd: match new line immediatelly after record without backslash

Code:
"(-,username,[^)]+.co.uk)$"

So i decided to rewrite script into perl, hoping that perl can deal with backslashes and end of line symbols. For this purpose I used a2p this way:

Code:
echo  'BEGIN {musr="(-,username,[^)]+.co.uk)"} {if ($0~musr) print $0}' | a2p.exe 
#!/usr/bin/perl
eval 'exec /usr/bin/perl -S $0 ${1+"$@"}'
    if $running_under_some_shell;
                        # this emulates #! processing on NIH machines.
                        # (remove #! line above if indigestible)

eval '$'.$1.'$2;' while $ARGV[0] =~ /^([A-Za-z_0-9]+=)(.*)/ && shift;
                        # process any FOO=bar switches

$, = ' ';               # set output field separator
$\ = "\n";              # set output record separator

$musr = '(-,username,[^)]+.co.uk)';

while (<>) {
    chomp;      # strip record separator
    if ($_ =~ $musr) {
        print $_;
    }
}

This generated perl script also matches both entries, however if I try modify this script to more specific I get the following errors:

1st:
Code:
$musr = "(-,username,[^)]+.co.uk)\\";
Trailing \ in regex m/(-,username,[^)]+.co.uk)\/ at perlmatch.pl line 18, <> line 1.

2nd:
Code:
$musr = "(-,username,[^)]+.co.uk)$";
Final $ should be \$ or $name at perlmatch.pl line 14, within string
syntax error at perlmatch.pl line 14, near "= "(-,username,[^)]+.co.uk)$""
Execution of perlmatch.pl aborted due to compilation errors.

3rd:
Code:
$musr = "(-,username,[^)]+.co.uk)\$";
[the output is nothing]

What I am doing wrong ? My question is also pointing to fact that if somebody needs to use script on several platforms (aix, solaris, linux) than using perl should be better approach that dealing with (non)GNU utils and various (g|n)awk versions etc. Regards
# 2  
Old 10-02-2012
both awk and perl are going to take the ( ) as grouping brackets, not literal ones, unless you escape them.
# 3  
Old 10-02-2012
The nice thing about awk/perl is you don't actually have to make big giant do-everything regexes to handle the logic.
Code:
$ cat mmatch.awk

{ N=0 }
     (NF==3) && ($1 == "(-") && ($2 == "username") && /\)\\$/ { T=$0 ; getline; N=1 }
N && (NF==3) && ($1 == "(-") && ($2 == "username") && /\)$/ { print T; print }

$ awk -F"," -f mmatch.awk data

(-,username,domain1.co.uk)\
(-,username,domain2.co.uk)

$


Last edited by Corona688; 10-02-2012 at 01:44 PM..
# 4  
Old 10-03-2012
Thank you for reply, sorry but I do not understand what you have done in awk script
# 5  
Old 10-03-2012
For each line that comes in:

1) Set N=0
2) If there's 3 tokens in the line, it begins with "(-", the second token is "username", and it ends with ")\", save the line in T, increment N, and get the next line.
3) If N is nonzero, the line has three tokens, begins with "(-", the second token is "username", and it ends with ")", print this line and the last.
# 6  
Old 10-03-2012
A slight change to your original awk should get the job done:

Code:
awk 'BEGIN {musr="[(]-,username,[^)]+.co.uk[)]\\\\?"} $0~musr' netgroup

Two of the \ chars are stripped by the shell, leaving \\ for awk
# 7  
Old 10-05-2012
Quote:
Originally Posted by Chubler_XL
A slight change to your original awk should get the job done:

Code:
awk 'BEGIN {musr="[(]-,username,[^)]+.co.uk[)]\\\\?"} $0~musr' netgroup

Two of the \ chars are stripped by the shell, leaving \\ for awk
No, awk just needs an irrational amount of backslashes:

Code:
$ echo 'BEGIN {musr="[(]-,username,[^)]+.co.uk[)]\\\\?"} $0~musr'

BEGIN {musr="[(]-,username,[^)]+.co.uk[)]\\\\?"} $0~musr

$

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