URL encoding a string in bash script

On CentOS, no extra package needed:

python -c "import urllib;print urllib.quote(raw_input())" <<< "$message"

Extending Rockallite's very helpful answer for Python 3 and multiline input from a file (this time on Ubuntu, but that shouldn't matter):

cat any.txt | python3 -c "import urllib.parse, sys; print(urllib.parse.quote(sys.stdin.read()))"

This will result in all lines from the file concatenated into a single URL, the newlines being replaced by %0A.

You want $MESSAGE to be in double-quotes, so the shell won't split it into separate words, then pass it to PHP as an argument:

ENCODEDMESSAGE="$(php -r 'echo rawurlencode($argv[1]);' -- "$MESSAGE")"