marys wrote:
Hello:
Hello,
Does anyone know how to use ‘awk’ in a script?
perl and awk have a lot of similar features so its usually preferable to
use perl in a perl program instead of awk.
It must have a
different syntax than the unix analog, as does the ‘grep’ command.
For grep, the syntax in the c-shell is:
“grep ‘string’ ,
It's the same in every shell because grep is a standalone command.
man grep
but for Perl the delimiters are slashes: $x = grep /
string/ line.
That's because in perl grep is a built-in function.
Maybe the same thing is going on with Perl.
I have searched the following sources with no help on awk:
perldoc -f ‘awk’
‘Beginning Perl’ by S. Cozen
‘CGI101’
and the O’Reilly books:
‘Learning Perl’ aka the llama book
‘Intemediate Perl’
‘Advanced Perl’
‘CGI Programming with Perl’
man awk
I have a file called /tmp/file.txt with one line:
field xxxx
for grepping on xxxx, the script is:
#!/usr/bin/perl -w
use CGI::Carp qw(fatalsToBrowser);
use CGI qw(:standard -no_xhtml);
#use CGI ':standard';
use strict;
use diagnostics;
my $q = new CGI;
print $q->header;
print $q->start_html(-title=>"mygrep");
my @infile;
my $q = new CGI;
open (FILEIN, "/tmp/file.txt") or die "Can't open /tmp/file.txt for
reading: $!\n!";
open (FILEOUT, ">/tmp/out.txt") or die "Can't open /tmp/out.txt for
writing: $!\n!";
system "chmod 755 /tmp/out.txt";
perldoc -f chmod
chmod 0755 '/tmp/out.txt' or warn "Cannot chmod '/tmp/out.txt' $!";
while ( defined(my $line=<FILEIN>) ){
In a while loop conditional defined() is implied for a readline.
chomp($line);
push (@infile,$line);
}
Or more simply:
chomp( my @infile = <FILEIN> );
my @zoom = grep(/xxxx/,@infile); #looks for 'xxxx' in @infile
Why didn't you just test for /xxxx/ in the while loop, then you wouldn't
need two arrays?
foreach (@zoom){
print $q->center($q->h3("\nNext line containing 'xxxx' is:
\n"),
$q->h3("$_\n"),
$q->h3("_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _") );
}
Or print this as you found /xxxx/ in the while loop and you wouldn't
need either array?
print $q->center($q->h2(" grep program is finished!\n"));
grep is a built-in Perl funtion, not an external program.
perldoc -f grep
The script works as it should for grep, but what if I want to output
$NF (=xxxx) when a line has the string ‘field’ in it? There must be
a way, but I can't find it.
What does $NF contain? I would guess that you want the line number
where /xxxx/ was found? If so:
while ( my $line = <FILEIN> ) {
next unless /xxxx/;
print $q->center(
$q->h3( "\nNext line containing 'xxxx' is:\n" ),
$q->h3( $_ ),
$q->h3( "At line number: $." ),
$q->h3( '_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _' )
);
}
John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall
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