GET9ROOT(3)

💖 GET9ROOT(3) — Library Functions Manual 💖

okay so bestie, welcome to the GET9ROOT(3) page from the Library Functions Manual. this one is literally about getting the path to the root of the Plan 9 tree, and it's giving niche-but-iconic. no cap. ✨

🌸 NAME 🌸

get9root, unsharp — get path to root of Plan 9 tree

✨ SYNOPSIS ✨

#include <u.h>
#include <libc.h>

char*     get9root(void)

char*     unsharp(char *path)

🦋 DESCRIPTION 🦋

So this tree of Plan 9 software is conventionally installed in but may be installed in other places — yes, the source lowkey leaves that first spot open, and we are not inventing a path, bestie — for example, users without the ability to write to /usr/local may wish to install it in their own home directories. The environment variable $PLAN9 should contain the path to the root.

get9root returns a static pointer to the pathname of root, first checking $PLAN9 and defaulting to .. static pointer, slay 💅

The lack of a fixed location for the Plan 9 tree makes it difficult to hard-code paths to files. unsharp replaces a leading #9 in path with the root of the tree. unsharp also replaces a leading #d with the path to the underlying system's file descriptor dup device, typically /dev/fd.

The string returned from unsharp, if different from path, should be freed with free (see malloc(3)) when no longer needed.

🚨 convention check: programs should never unsharp paths obtained from user input. periodt.

🎀 EXAMPLE 🎀

The plumber(4) uses this code to find unrooted file names included by plumb rules.

snprint(buf, sizeof buf, "#9/plumb/%s", name);
fd = open(unsharp(buf), OREAD);

🌈 SOURCE 🌈

• /src/lib9/get9root.c
• /src/lib9/unsharp.c

💜 SEE ALSO 💜

• intro(4)

💀 BUGS 💀

Get9root could be smarter about finding the tree when $PLAN9 is not set.

k bye bestie — this was GET9ROOT(3) from the Library Functions Manual, source/version GET9ROOT(3), and the footer didn't give us a date, so that's the whole vibe. stay iconic 🫶✨