Question

I’d like to replace (as an example) the text of lines 5-15 in a file with the text from lines 6-15 from another file. But I’d like to do this over about 2000 files, and would rather not have to do it manually.

I could script something in perl, but I’d like to try to do it with any built-ins possible.

Answer 1

I’d probably use sed

for file in bar baz bam; do
    newfile=$(mktemp)
    (sed '5q' $file; sed -n '6,15p' foo; sed '1,15d' $file) > $newfile
    mv -f $newfile $file
done

or Perl

#!/usr/bin/env perl

use v5.6;  # lexical filehandles need Perl >= 5.6

# usage: $0 foo bar baz bam
# replaces lines 4-15 of qw(bar baz bam) with lines 6-15 of foo 

my @ins;

{
    open my $fh, shift;
    while (<$fh>) {
        push @ins, $_ if 6 .. 15;
        last if $. >= 15;
    }
}

$^I = '';

while (<>) {
    print if not 5 .. 15;
    print @ins if $. == 4;
}
continue {
    close ARGV if eof ARGV;
}

but ed works too.

echo '6,15wq foo-part' | ed foo
for i in bar baz bam; do
    echo -e '5,15d\n4r foo-part\nwq' | ed $i
done
rm -f foo-part