RE: reading/writing to a ascii file
ok let's say I have a 500,000 line file... What I want is for the script to read the file in line by line and only change the 1 line I am looking for. ex: line 550 contains the line I am looking for I want to change that line and not have to re-create the file. You could do this: perl -i -p -e s/search/replace/ig $filename Good luck! -Erich- ___ Perl-Win32-Users mailing list [EMAIL PROTECTED] To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
RE: reading/writing to a ascii file
Ryan, it's easier than you think:
open(IN, $inputfile) or die can't open $inputfile: $!;
open(OUT,$outputfile) or die can't open $outputfile: $!;
while (IN){
s/$string/$replacement/g;
print OUT $_;
}
close IN;
close OUT;
rename($outputfile, $inputfile) or die can't rename... $!;
--
Mark Thomas[EMAIL PROTECTED]
Internet Systems Architect User Technology Associates, Inc.
$_=q;KvtuyboopuifeyQQfeemyibdlfee;; y.e.s. ;y+B-x+A-w+s; ;y;y; ;;print;;
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RE: reading/writing to a ascii file
Title: RE: reading/writing to a ascii file
That is still opening and reading the entire file and then creating an entire new file... I may run into instances where the file will be opened and modified many times.
-Original Message-
From: Thomas, Mark - BLS CTR [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, October 28, 2003 9:53 AM
To: 'Farrington, Ryan'; [EMAIL PROTECTED]
Subject: RE: reading/writing to a ascii file
Ryan, it's easier than you think:
open(IN, $inputfile) or die can't open $inputfile: $!;
open(OUT,$outputfile) or die can't open $outputfile: $!; while (IN){
s/$string/$replacement/g;
print OUT $_;
}
close IN;
close OUT;
rename($outputfile, $inputfile) or die can't rename... $!;
--
Mark Thomas [EMAIL PROTECTED]
Internet Systems Architect User Technology Associates, Inc.
$_=q;KvtuyboopuifeyQQfeemyibdlfee;; y.e.s. ;y+B-x+A-w+s; ;y;y; ;;print;;
RE: reading/writing to a ascii file
That is still opening and reading the entire file and then creating an entire new file... No, it's not. It reads only one line at a time into memory. This is quite different from your version which read the entire file into memory. Are you looking to avoid *both* reading the file into memory and creating a temp file? If so, look into the Tie::File module. I believe you'd have to lock the file to prevent other processes from reading the file while it is tied. -- Mark Thomas[EMAIL PROTECTED] Internet Systems Architect User Technology Associates, Inc. $_=q;KvtuyboopuifeyQQfeemyibdlfee;; y.e.s. ;y+B-x+A-w+s; ;y;y; ;;print;; ___ Perl-Win32-Users mailing list [EMAIL PROTECTED] To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
RE: reading/writing to a ascii file
Ok guys here is the pickle I'm in now =-) I need to read from
a ASCII file and only modify the lines that match a variable.
I do not want to read the entire file into memory and write
the entire file out each time I need to make a change.
Here is what I am doing that reads the entire file and
re-writes the entire file:
$var1 = '106253498';
open(FILE, my.file);
@file = FILE;
close(FILE);
open(FILE, my.file);
chomp @file;
foreach my $line (@file){
if ($line =~ /^$var1\|/){
#do my data changes
$line = asdf1234;#where asdf1234 is my changes
}
print FILE $line . \n;
}
close(FILE);
Can anyone offer a suggestion? My issue is that the data that
is coming in is x length (where x is a dynamic space) and the
value I am writing back to the line can be a max of x+10 and
a min of x-10..
You could use Tie::File...
use Tie::File;
$var1 = '106253498';
tie my @hash, 'Tie::File', my.file;
foreach (@hash) {
if (/^$var1\|/) {
$_ = asdf1234;
}
}
untie @hash;
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