sed in perl

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

Hi All, i have a problem with using sed in a perl script. Requirement: Read a csv file (file1) containing certain pattern, match the pattern in another text file (file2) and delete it where ever its occurring.

file1:

abc/def
sde/dfg/htf
[download]

file2:

abc/def = 100
sde/dfg/htf = 230
dad/fry = 000
[download]

in the end only dad/fry = 000 should remain in file2.

I cannot install any package, so have to use the default perl options.

Since my file1 contains special character "/" , i have escaped it in my code.

my sed command is working fine if I try to run it without loop, i.e for one pattern only. As soon as I add it in loop, it fails.

my code:

my $var = "sde\\/dfg\\/htf";
`sed -i '/$var/d' ADT_DVEBMGS33_ldciadt`;
[download]

The above works fine.

i tried to encorporate in a loop


my $len = scalar @delete;
for ( my $i = 0; $i <=$len; $i++){
        my $first = $delete[$i];
        chomp $first;
        $first =~ s:/:\\\\/:g;
        `sed -i "/$first/d" file2`;
}
[download]

error

<c> sed: -e expression #1, char 10: extra characters after command sed: -e expression #1, char 0: no previous regular expression

Comment on sed in perl Select or Download Code

Replies are listed 'Best First'.
Re: sed in perl by Corion (Patriarch) on Nov 11, 2019 at 10:33 UTC
Why are you using `sed` when you can use Perl directly? `open my $fh1, '<', "file1" or die "Couldn't read 'file1': $!"; my %delete = map { s/\s$//; $_ => 1 } <$fh1>; open my $fh2, '<', "file2" or die "Couldn't read 'file2': $!"; while( <$fh2>) { my( $key, $value ) = split /\s=/; if( ! $delete{ $key }) { print $_; } else { # skip this key }; };` [download] If you want to keep on using `sed`, my advice is to print all the commands you're launching and then inspecting them or running them from the command line separately.	[reply] [d/l] [select]
Re^2: sed in perl by GauCho (Initiate) on Nov 14, 2019 at 06:05 UTC
I tried printing the sed command and to my surprise, sed is not working as expected. i get "/d' <file2>" as command and sed is nowhere part of the command. i will try out the perl code!	[reply]
Re: sed in perl by Anonymous Monk on Nov 11, 2019 at 10:40 UTC
Hi. Why not write the whole enchilada in sed? I mean come on very much. ;). Csv is too complexed for sed. https://metacpan.org/pod/Text::CSV_XS#The-examples-folder, Basic debugging checklist, String::ShellQuote , sed isn't working within a perl script	[reply]


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