How to tell bash not to expand $_ variable?

Question

I want to use some perl line, like this:

perl -pe "$_=~s///e"

The problem is, bash keeps expanding the "$_" variable. I could put the perl expression into single quotes, but that would prevent me from adding some variables into a script.

Is there a way stop bash from expanding "$_" variable?

Answer 1

perl -pe '$_=~s///e'

or

perl -pe "\$_=~s///e"

Answer 2

First off: You know that you can use $ENV{myvariable} to access environment variables, right? And that you do not need to specify $_ when using m//, s/// and tr///?

Furthermore, if you want to pass variables to perl, there are other ways of doing that besides trying to interpolate shell variables into your perl code.

perl -we 'my ($var1, $var2, $var3) = @ARGV;' "$MYFOO" "$BAR" "$baz"

If your shell variables do not contain whitespace, you can dispense with the quoting.

Now, if you want to use the -p or -n switches, there are ways around that too.

perl -pwe 'BEGIN { my $var1 = shift; my $var2 = shift } #code goes here'
    "$MYFOO" "$BAR" file1 file2 

Using shift in a BEGIN statement will remove variables from @ARGV so that they are not used by the implicit while loop of the -p and -n switches.