Issue with perl regex search and replace with environment variable

Question

I'm running a GCE VM with Ubuntu 18, and having an issue with a perl command.

export ip_addr=`hostname -i`
echo "set \$ip_addr_priv \"{my_ip_address}\"" | sudo perl -n -e 's/(\$ip_addr_priv) +"\{([a-zA-Z0-9_]+)\}"/\1 "$ENV{ip_addr}"/g; print;'

When I run this in the command line, I get the following output:

set $ip_addr_priv ""

Instead of something like this:

set $ip_addr_priv "127.0.0.1"

What am I doing wrong?

Maybe the environment variable is not exported into the `sudo` environment? See also [How to keep environment variables when using sudo?](https://stackoverflow.com/q/8633461/2173773) — Håkon Hægland, Oct 28 '19 at 10:52

score 3 · Accepted Answer · answered Oct 28 '19 at 10:56

By default (and by design), sudo doesn't pass the current user's environment on to the new process.

You can override this behaviour with the -E command line flag.

echo "set \$ip_addr_priv \"{my_ip_address}\"" | sudo perl -n -e 's/(\$ip_addr_priv) +"\{([a-zA-Z0-9_]+)\}"/\1 "$ENV{ip_addr}"/g; print;'
set $ip_addr_priv ""

Vs:

echo "set \$ip_addr_priv \"{my_ip_address}\"" | sudo -E perl -n -e 's/(\$ip_addr_priv) +"\{([a-zA-Z0-9_]+)\}"/\1 "$ENV{ip_addr}"/g; print;'
set $ip_addr_priv "127.0.1.1"

Issue with perl regex search and replace with environment variable

1 Answers1