wcj75019 has asked for the wisdom of the Perl Monks concerning the following question: 

 
Hello Monks,
I can't get my script to add another if statement after $1.
This is the file I want to modify:
#!/sbin/sh

# Run rctladm to configure system resource controls based on the setti
+ngs
# previously saved by rctladm.  See rctladm(1m) for instructions on ho
+w to
# modify resource control settings.
#
if [ -f /etc/rctladm.conf ] && [ -x /usr/sbin/rctladm ]; then
        /usr/sbin/rctladm -u
fi

I want to add another if statement after the last if/fi.

Thanks,

[download]
#!/usr/bin/perl -w
use strict;
open SYS, "sysetup";
open OUT, '>', "/tmp/sysout";
my $here=<<HERE;
                if /usr/bin/pgrep -x -u 0 -P 1 ltps& >/dev/null 2>&1; 
+then
                        echo "$0: ltps is already running"
                        exit 0
                fi
HERE
while(<SYS>){
        s/^(if.*rctladm.conf.*?fi)/$1\n$here/m;
        print OUT;
}

[download]

Replies are listed 'Best First'.
Re: add after $1
by hipowls (Curate) on Mar 20, 2008 at 22:25 UTC

    You are reading in single lines and then testing if that line has an 'if' and a 'fi' in it. Since the if statement you are looking for spans multiple lines you won't find it that way.

    Your choices are to read in the entire script to a single string or to process the file a line at a time remembering the state of your search. The first is easiest and, assuming your script is not several hundred Megabytes in size, practical.

    use strict;
use warnings;

my $here=<<HERE;
                if /usr/bin/pgrep -x -u 0 -P 1 ltps& >/dev/null 2>&1; 
+then
                        echo "$0: ltps is already running"
                        exit 0
                fi
HERE

my $file = do { local $/; <DATA> };
$file =~ s/^(if.*?rctladm\.conf.*?fi$)/$1\n$here/ms;
print $file;

__DATA__
# Run rctladm to configure system resource controls based on the setti
+ngs
# previously saved by rctladm.  See rctladm(1m) for instructions on ho
+w to
# modify resource control settings.
#
if [ -f /etc/rctladm.conf ] && [ -x /usr/sbin/rctladm ]; then
        /usr/sbin/rctladm -u
fi

    [download]
    produces 
    # Run rctladm to configure system resource controls based on the setti
+ngs
# previously saved by rctladm.  See rctladm(1m) for instructions on ho
+w to
# modify resource control settings.
#
if [ -f /etc/rctladm.conf ] && [ -x /usr/sbin/rctladm ]; then
        /usr/sbin/rctladm -u
fi
                if /usr/bin/pgrep -x -u 0 -P 1 ltps& >/dev/null 2>&1; 
+then
                        echo "Perl-1.pl: ltps is already running"
                        exit 0
                fi

    [download]
    You may want to look at the indenting of your replacement text.

[reply]
[d/l]
[select]
      SWEEEET! Thank You hipowls!
[reply]
Re: add after $1
by NetWallah (Canon) on Mar 20, 2008 at 22:11 UTC
    Update::I forgot to mention - you need to slurp the file, as hipowls(++) indicates below.

    Your regex needs two changes:

    • Escape the period
    • Add the \s modifier.
             From "perldoc perlre":
                 Used together, as /ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively, just after and just before newlines within the string.
    This works: 
    s/^(if.*rctladm\.conf.*fi)/$1\n$here/sm;

    [download]
    However, may I suggest the following alternatives:
    • Replace the entire shell script with perl.
    • Insert a line at the end of the original script, that calls another (bash) script. Use perl to generate the second script. This way, the first script remains unmodified - easier to enhance and debug.

         "As you get older three things happen. The first is your memory goes, and I can't remember the other two... " - Sir Norman Wisdom

[reply]
[d/l]
      For some reason. Still, the $here doesn't print after the last fi. Thanks,
[reply]

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