Remove a line from a file using perl one liner

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

Hello Monks,
I like to remove the line Alias /icons/ "/ans/sttp/icons/" from the file one.txt without opening and closing the file. I mean i am looking for a perl one line command.

Input File(one.txt):
Alias /ans_win/ "/ans/win/"
Alias /icons/ "/ans/sttp/icons/"
Alias /name/ "ans/name"


Mycode:
open(OH,">two.txt") or die "Could not write file two.txt";
open(FH,"one.txt") or die  "Could not open file one.txt";
while(<FH>){

if (($_ =~ /Alias/) && ($_ =~ /icons/)){
print"Data=> $_\n";
}else{
print OH $_;
}
}
close OH;
close FH;

$out = "mv two.txt one.txt";
system($out);

My Expected output file:
Alias /ans_win/ "/ans/win/"
Alias /name/ "ans/name"
[download]

Can you help here please?
--Nathan

Comment on Remove a line from a file using perl one liner Download Code

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Re: Remove a line from a file using perl one liner by gwadej (Chaplain) on Mar 19, 2009 at 13:54 UTC
Look in perlrun for the -i, -e, and -n command line switches. Using these two switches and the logic from your code above, the problem is pretty easy to solve. `perl -i -ne'print unless /Alias/ and /icons/;' one.txt` [download] Update: as Bloodnok points out, this could be considered dangerous. A safer version is: `perl -i.bak -ne'print unless /Alias/ and /icons/;' one.txt` [download] which leaves the original as one.txt.bak. G. Wade	[reply] [d/l] [select]
Re: Remove a line from a file using perl one liner by Bloodnok (Vicar) on Mar 19, 2009 at 13:50 UTC
Depends on the OS, but on *NIX, `perl -ne 'next if m,^Alias /icons/,; print' < one.txt > tmp.txt && mv +tmp.txt one.txt` [download] or, if you're feeling brave... `perl -i -ne 'next if m,^Alias /icons/,; print' one.txt` [download] should do the trick. A user level that continues to overstate my experience :-))	[reply] [d/l] [select]
Re: Remove a line from a file using perl one liner by smanicka (Scribe) on Mar 19, 2009 at 14:05 UTC
you should be able to do an inplace edit. `perl -pi -e 's/$string_to_be_removed//g' full_path/one.txt` obviously if you use windows, in-place edit won't work.You can try `#!/usr/bin/perl BEGIN {(STDERR = STDOUT) \|\| die;} use diagnostics; use warnings; use strict; $\| = 1; my $file = full_path/one.txt; @ARGV = $file; $^I = '~'; while (<>) { binmode ARGVOUT if $. == 1; s/$string_to_be_removed//g; print; }` [download] i am just trying to help.Please do check if the windows code works.I am not sure if it could throw any errors.It works fine for a substitute for me on activeperl on windows xp.I also do the replace on all files in a directory. -Smanicka	[reply] [d/l] [select]
Re: Remove a line from a file using perl one liner by olus (Curate) on Mar 19, 2009 at 13:56 UTC
`perl -pi -e 's#Alias./icons/.##s;' one.txt`	[reply] [d/l]
Re^2: Remove a line from a file using perl one liner by ikegami (Patriarch) on Mar 19, 2009 at 14:00 UTC
Lines in httpd conf files are sometimes indented. `perl -pi -e's#^\s+Alias./icons/.##s' one.txt` [download]	[reply] [d/l]
Re^3: Remove a line from a file using perl one liner by olus (Curate) on Mar 19, 2009 at 14:09 UTC
You're absolutely right. Thanks I'll go and write on the white board 'assumptions are evil' :o)	[reply]
Re^3: Remove a line from a file using perl one liner by Anonymous Monk on Mar 19, 2009 at 14:11 UTC
Thanks All ...It worked well for me. Thanks a lot.	[reply]