rederr

rederr is a small tool that invokes another command and propagates its stdout as-is and its stderr in ANSI red.

Just prefix any command line of your choice with rederr and it will make it easy for to figure out what is error and what is output.

Example:

# cat > test.sh <<EOF
#!/bin/sh

echo "This is going to stdout"
echo "And this is going to stderr" >&2
EOF

# rederr test.sh
This is going to stdout
And this is going to stderr

And yeah, GitHub-style Markdown doesn't really allow for colours. Let's just say the last line in the above output is now red.