mjhjmtu

I want to run a utility for replace values matching a regular expression. This means for every match of a regular expression, call the utility with the characters comprising the match. The output of the utility replaces the original characters.

For illustration purposes using factor:

$ factor 230
230: 2 5 23

So using this utility, I want to pick out the integers, call factor with the integer, and replace the original integer with the output of factor.

This is what I would expect on a sample input:

$ [code] <<< "Given the numbers with factors: 27, 13, 230, and 19, it is evident which are primes."
Given the numbers with factors: 27: 3 3 3, 13: 13, 230: 2 5 23, and 19: 19, it is evident which are primes.

I thought this might work, but it looks like it's trying to interpret the input directly. Using sed (GNU sed) 4.2.2.

$ sed -E 's/([0-9]+)/factor 1/ge' <<< 'Given the numbers with factors: 27, 13, 230, and 19, it is evident which are primes.'
sh: 1: Given: not found

Obviously I'm not understanding what the e flag does. Removing the e shows that the regular expression is correctly pulling out the integers and passing them as 1.

I tried doing this in awk:

$ awk 'r = gensub(/([0-9]+)/, system("factor \1"), "g"); print r' <<< 'Given the numbers with factors: 27, 13, 230, and 19, it is evident which are primes.'
1:
Given the numbers with factors: 0, 0, 0, and 0, it is evident which are primes.

I'm not sure where the 1: comes from, but it's apparent that it's printing just the return code from system. There doesn't appear to be a way to capture the standard output from a command in awk.

Is what I'm asking for possible using the core utilities?

Possible in Perl. Using split, map, scalar, lc, reverse, ucfirst, join. A bit more complex than I originally thought because of the commas and context sensitivity of matching.

#!/usr/bin/perl
use warnings;
use strict;

sub rev 
 my ($string) = @_;
 my @words = split /(W+)/, $string;
 my @caps = map scalar(/^[[:upper:]]/), @words;
 $_ = /w/ ? lc reverse : $_ for @words;
 shift @caps and $_ = ucfirst for @words;
 return join "", @words


use Test::More tests => 1;
my $r = rev('Hello, my name is Yimin Rong.');
is $r, 'Olleh, ym eman si Nimiy Gnor.';

Try the below awk solution:

echo "Hello" | awk ' for ( i=length($0);i>0;i-- ) if (i == length($0) ) printf "%s",toupper(substr($0,i,1)) else printf "%s",tolower(substr($0,i,1)) printf "n" '

Take each letter of the word character by character stating from the last. If it is the last character, convert to upper case and print otherwise print lower case.

Run the following :

 perl -pe 's/(d+)/qx(factor $1) =~ s|n||r/ge' input-file.txt

The reason why your sed command is not working is because sed will execute the entire pattern space unlike Perl which is aligned with how you were thinking and executes just as much as is on the rhs of the s/// command and replaces tonly that much with the command output.

And that's precisely why if you notice sed was cribbing abt "Given:" utility not found. Given was the beginning of your pattern space. HTH

Run the following:

perl -pe 's/(d+)/qx(factor $1) =~ s|n||r/ge' input-file.txt