The `s6-quote-filter` program

s6-quote-filter acts as a filter, quoting lines it reads on stdin and writing the quoted lines to stdout.

Interface

     s6-quote-filter [ -u ] [ -d delim ]

s6-quote reads lines on stdin; it quotes every line, putting it inside double quotes and escaping all dubious characters
It writes the quoted strings to stdout
It exits 0 on EOF

-u : do not put read lines inside double quotes, only escape characters if needed
-d delim : use the first character of delim as a quote character, instead of double quotes

Quoted strings are guaranteed to be pure printable ASCII, without control characters.
Quoted strings can be unquoted via the s6-unquote or s6-unquote-filter programs.