I want to replace the middle of some text with a string from an array.
#!/bin/bash
array=(1 2 3 4 5 6)
for i in "${array[@]}"; do
# doesn't work
echo "some text" | perl -pe 's|(some).*(text)|\1$i\2|'
done
I am using perl regex instead of sed for its easier non-greedy matching support. What's the correct syntax for getting the value of $i in there?
Just replace the single quotes around the regexp with double quotes.
#!/bin/bash
array=(1 2 3 4 5 6)
for i in "${array[@]}"; do
echo "some text" | perl -pe "s|(some).*(text)|\1$i\2|"
done
Single quotes do not expand the variable.
perl -pe "s|(some).*(text)|${1}$i\2|"There's a couple of approaches you could take. The problem is, the string you're passing to perl is single quoted, which means it won't be interpolated. That's normally good news, but in this case you're passing through $i literally, and there's no perl variable with that name.
One approach is to export it an then read it in via the %ENV hash:
export VALUE=3;
perl -e 'print $ENV{'VALUE'},"\n";'
Otherwise, you 'just' need to interpolate the string first:
VALUE=3
perl -e "print $VALUE;"
Although in your example - I'd be suggesting don't bother using shell at all, and rewrite:
#!/usr/bin/perl
my @array = qw (1 2 3 4 5 6);
foreach my $element ( @array ) {
my $text = "some text";
$text =~ s|(some).*(text)|$1$element$2|;
print $text,"\n";
}
There is a bit dirty trick that actually works in most cases: just end the string in the single quotes, insert the bash variable, and restart the single-quoted string. It's important not to insert any spaces between those three parts, as in the following sample:
#! /bin/bash
array=(1 2 3 4 5 6)
for i in "${array[@]}"; do
# doesn't work
echo "some text" | perl -pe 's|(some).*(text)|${1}'$i'${2}|'
done
Note that I had to replace \1 with ${1}, otherwise perl would interpret it as \11, \12, etc.
Actually, there is another problem existing. If you run code below, you won't get expected result.
#!/bin/bash
array=(1 2 3 4 5 6)
for i in "${array[@]}"; do
echo "some text" | perl -pe "s|(some).*(text)|\1$i\2|"
done
It is caused that after bash variable is expanded, perl code becomes perl -pe "s|(some).*(text)|\11\2|", then you got \11 not \1 so match value is wrong.
