twiddle

Synopsis

$twiddle(<tilde-expansion>)

Technical

Expands a leading ~ in the entire argument as a home-directory reference. ~ and ~/path use EPIC's stored home directory. ~user and ~user/path look up the named system account and substitute its home directory. A suffix after the slash is retained.

EPIC initializes its own home directory from the account database, falling back to HOME and then / if unavailable. Changing the environment later does not update that stored value. Named-user lookup uses getpwnam_r on each call.

If the first character is not ~, the input is copied unchanged, subject to the pathname buffer limit. There is no word parsing: spaces and literal quotation marks are part of the argument. Quoting the whole path prevents expansion because its first character is then a quotation mark.

Practical

Use this function to expand a home-relative filename before passing it to another operation. It does not check that the file exists, create it, resolve symlinks, remove .., expand wildcards, or change the working directory. realpath provides separate path-resolution behavior.

Returns and restrictions

The expanded pathname, the unexpanded input if it does not begin with ~, or empty for an unknown user or account-lookup error. Empty input returns empty. Errors are not distinguished or printed by this function.

Output is bounded by EPIC's Filename buffer (PATH_MAX + 1 bytes) and can be silently truncated. Named-user lookup uses a fixed 16384-byte account-information buffer; lookup errors, including an insufficient buffer, return empty. There are no options, settings, or server requirements.

Examples

$twiddle(~)                 Returns EPIC's stored home directory.
$twiddle(~/notes.txt)        Expands the home directory and retains /notes.txt.
$twiddle(~jvs)              Returns the home directory for user jvs, if found.
$twiddle(~nosuchuser)       Returns empty if that user does not exist.
$twiddle(blah)             Returns blah.

Source

Handler: source/functions.c. Expansion: expand_twiddle. Stored home initialization: source/irc.c. Path buffer: include/irc_std.h.