REALPATH(1) General Commands Manual Fully-rendered PDF

realpath — get canonical file path

realpath [-e|-E|-m|-s] [-P|-L] [-z] file…

Finds the canonical path (one which starts at the root (/), has only single /es, and contains no .. nor . elements) to each file, followed by a new-line (), to the standard output stream; these are determined with varying degrees of laxness:

with -e:
file must exist, and its absolute path (realpath(3)) is written,
by default (-E):
otherwise its parent directory must exist, its (potential) absolute path is written,
with -m:
any prefix of file must exist, and the nonexistent bits are pasted at the end, then .. and . elements are processed with string substitutions (like cd(1) -L).
With -s:
file is processed with string substitutions only.

, --canonicalize-existing
file (every component of file) must exist.
Every component but the last must exist (file or file's parent directory). If file doesn't exist, the nonexistent basename is appended verbatim. This is the default.
, --canonicalize-missing
No component needs to exist, longest existing prefix of file is canonicalised as-if with -e, then the nonexistent bit is pasted on the end, and -L processing applied.
, --strip, --no-symlinks
Apply -L processing only. The filesystem is not consulted at all.

, --physical
Do not pre-process file (resolve it as-if given to cd(1) -P or open(2)). This is the default.
, --logical
Pre-process each file as-if given to cd(1) -L, flattening away .. and .s: a/b/./c/../d turns into a/b/d, regardless of what c is (this is a string operation, the filesystem is not consulted), before giving it to -eEms.

, --zero
Write a NUL after the canonical path of each file instead.

if a file (-e) or its parent (-eE) don't exist. An error is also issued to the standard error stream in this case.

$ ls -l src
lrwxrwxrwx 1 root root 14 2020-04-15  src -> /usr/local/src
$ realpath src
/usr/local/src
$ realpath src/..
/usr/local
$ realpath -L src/..
/home/cicada

$ ls
ksmctl.c
$
realpath . ksmctl.c rp-pppoe one/piece/.. /usr/local/src /usr/local/src/ksmctl.c /usr/local/src/rp-pppoe realpath: one/piece/..: No such file or directory $ realpath -e . ksmctl.c rp-pppoe one/piece/.. /usr/local/src /usr/local/src/ksmctl.c realpath: rp-pppoe: No such file or directory realpath: one/piece/..: No such file or directory $ realpath -m . ksmctl.c rp-pppoe one/piece/.. /usr/local/src /usr/local/src/ksmctl.c /usr/local/src/rp-pppoe /usr/local/src/one

ls(1), pwd(1), readlink(1), symlink(2), realpath(3)

Conforms to IEEE Std 1003.1-2024 (“POSIX.1”). -msPLz and more than one file are extensions, compatible with the GNU system.

The standard mandates -EP behaviour only if -E is specified. Many implementations default to some combination of -e and -L.

Appeared in FreeBSD 4.3 (2001-04) and FreeBSD 5.0 (2003-01) (originally slated for FreeBSD 5.0 and appears in the FreeBSD 5.0 tag, but the manual was later changed to say it originated in even though it's not in the FreeBSD 4.3 tag, but it in the releases) as realpath(1) ("return resolved physical path"), synopsised as

realpath path

It's actually the same binary as pwd: it writes getcwd(3) if invoked with no arguments, and realpath(3) if with one. This is equivalent to having a default file of ".". This corresponds to present-day -e.

FreeBSD 5.1 (2003-07) unlinks realpath from pwd and removes the default-"." behaviour.

FreeBSD 8 (2009-11) sees a SYNOPSIS of

realpath [-q] path [...]
-q is equivalent to 2>/dev/null.

FreeBSD 9 (2012-01) sees a SYNOPSIS of

realpath [-q] [path ...]
Yes, the default file ... is, ".".

realpath mksh(1) R35 (2008-07) ships realpath as a built-in (used when no flags are given), writing realpath(3) directly (-e-equivalent behaviour).

mksh(1) R39b (2010-01) changes it to behave more like this implementation's -EL (functionally this may actually be closer to -m).

OpenBSD 7.1 (2022-04) includes realpath(1) ("print the canonicalized absolute pathname"), with a SYNOPSIS of

realpath [-q] file
writing realpath(3) directly (-e-equivalent behaviour).

NetBSD 10 (2024-03) includes a IEEE Std 1003.1-2024 (“POSIX.1”)-compatible readlink(1) ("return resolved canonical path"), synopsised as

realpath [-eEq] [path ...]
with the default path being "." and the default behaviour being -E.

coreutils 8.15 (2012-01) adds realpath(1) ("print the resolved"), synopsised as:

realpath [OPTION]... FILE...
where OPTIONS is actually any of -emsPLz, as present-day, and -q, --relative-to=FILE, --relative-base=FILE 🙄.
December 16, 2024 voreutils 5a9f9f29