Urlencode

$urlencode(text) is a compatibility alias in builtins, not a registered C built-in. It returns $xform(+url text). Its defining script must be loaded; default startup normally loads it. urldecode supplies the reverse wrapper.

The direct xform equivalent is:

$xform(+url hello there)

This returns hello%20there. The encoder preserves ASCII letters, digits, -, _, ., and ~. Every other byte becomes % followed by two uppercase hexadecimal digits. A space becomes %20, not +; a literal plus becomes %2B. Empty input returns empty.

The operation encodes bytes without character-set conversion. UTF-8 characters can therefore produce several percent escapes. It does not parse a URL or preserve reserved separators such as /, :, ?, and &, so apply it to the component or data value that needs escaping rather than blindly treating an entire URL as one component.

Ordinary function input is a C string, so embedded NUL bytes cannot be supplied intact that way. A single xform chain can retain binary intermediate lengths and end with URL encoding to return text safely. See xform for chain syntax and limits.

Percent encoding is not a general substitute for shell quoting, path validation, or protocol validation. exec and any later decoding/evaluation stage have their own argument rules. This function performs no network request or file transfer.

Source references

• script/builtins: URL compatibility wrappers.
• source/ircaux.c: unreserved-byte table, percent encoder, and transform registration.
• source/functions.c: xform interface and current registry.