Any recommendations for a library that can do stri...

# getting-started

[Rob Elliot]

Any recommendations for a library that can do string escaping, other than org.apache.commons.text.StringEscapeUtils?

[Joffrey]

String escaping for what? Usually it comes with whatever you want to escape it for. For instance HTTP libraries likely have URL-encoding functions, markdown libraries for markdown escaping etc

[Rob Elliot]

Shell. I want to take a bunch of strings representing an executable and its arguments, of the form you would pass to java.lang.ProcessBuilder(String... command), and print them in a form that could be passed to sh -c and would work. Single quotes around each string would mean replacing any single quotes in the string with '\'' - that might be all that's needed

[ephemient]

the List<String>/vararg String methods of ProcessBuilder pass arguments to the executable directly, without going through shell, which avoids the need for escaping. why do you need something to pass to sh -c?

[Joffrey]

@ephemient some commands are actually shell built-ins, which might be the reason why sh -c is needed

[Joffrey]

@Rob Elliot I hope you don't have to support windows' cmd, otherwise good luck with quoting

[ephemient]

yeah there is no reliable quoting method on Windows since every program gets to interpret the command line in their own way…

[Rob Elliot]

For toString purposes, really - I want to represent it in a way that is easy for me to read & copy into an actual shell if I want to play with it.

[Rob Elliot]

Not interested in supporting Windows

[ephemient]

@Joffrey there are very few shell builtins I'd expect to be called by non-shell users - the only one I can think of is time which exists as a separate executable on many systems anyway

[Rob Elliot]

This is naive, I presume I will shortly find a test that breaks it. Also there must be more efficient ways that multiple contains.

private fun String.escape() = if (contains(' ') || contains('\'')) {
  "'${replace("'", "'\\''")}'"
} else this

[ephemient]

anything involving `#$&();<>?[\]`{|}~` is liable to be interpreted by the shell, and other whitespace characters such as \t are usually in $IFS too

[ephemient]

also !^ may special meaning depending on the shell

[Rob Elliot]

Thanks, that's very helpful

[ephemient]

if you want to see how Bash generates quoted representations of strings and have Bash 4.0+ (notably, not macos),

ProcessBuilder("/bin/bash", "-c", "echo \"\${@@Q}\"", "-s", "<\$hello>", "world!\n").start().inputReader().readLine()
// returns '<$hello>' $'world!\n'

but note that the $'' syntax is Bash-specific

[ephemient]

lots of shell-specific stuff is pretty shell-specific