junegunn
commented
2 years ago Which version of macOS are you running? My installation of readlink supports -f.
$ /usr/bin/readlink --help
/usr/bin/readlink: illegal option -- -
usage: readlink [-fn] [file ...]$ man readlink | col -b | pbcopySTAT(1) General Commands Manual STAT(1)
NAME
stat, readlink – display file status
SYNOPSIS
stat [-FLnq] [-f format | -l | -r | -s | -x] [-t timefmt] [file ...]
readlink [-fn] [file ...]
DESCRIPTION
The stat utility displays information about the file pointed to by file.
Read, write, or execute permissions of the named file are not required, but
all directories listed in the pathname leading to the file must be
searchable. If no argument is given, stat displays information about the
file descriptor for standard input.
When invoked as readlink, only the target of the symbolic link is printed.
If the given argument is not a symbolic link and the -f option is not
specified, readlink will print nothing and exit with an error. If the -f
option is specified, the output is canonicalized by following every symlink
in every component of the given path recursively. readlink will resolve
both absolute and relative paths, and return the absolute pathname
corresponding to file. In this case, the argument does not need to be a
symbolic link.
The information displayed is obtained by calling lstat(2) with the given
argument and evaluating the returned structure. The default format
displays the st_dev, st_ino, st_mode, st_nlink, st_uid, st_gid, st_rdev,
st_size, st_atime, st_mtime, st_ctime, st_birthtime, st_blksize, st_blocks,
and st_flags fields, in that order.
The options are as follows:
-F As in ls(1), display a slash (‘/’) immediately after each pathname
that is a directory, an asterisk (‘*’) after each that is
executable, an at sign (‘@’) after each symbolic link, a percent
sign (‘%’) after each whiteout, an equal sign (‘=’) after each
socket, and a vertical bar (‘|’) after each that is a FIFO. The
use of -F implies -l.
-L Use stat(2) instead of lstat(2). The information reported by stat
will refer to the target of file, if file is a symbolic link, and
not to file itself. If the link is broken or the target does not
exist, fall back on lstat(2) and report information about the link.
-f format
Display information using the specified format. See the Formats
section for a description of valid formats.
-l Display output in ls -lT format.
-n Do not force a newline to appear at the end of each piece of
output.
-q Suppress failure messages if calls to stat(2) or lstat(2) fail.
When run as readlink, error messages are automatically suppressed.
-r Display raw information. That is, for all the fields in the stat
structure, display the raw, numerical value (for example, times in
seconds since the epoch, etc.).
-s Display information in “shell output” format, suitable for
initializing variables.
-t timefmt
Display timestamps using the specified format. This format is
passed directly to strftime(3).
-x Display information in a more verbose way as known from some Linux
distributions.
Formats
Format strings are similar to printf(3) formats in that they start with %,
are then followed by a sequence of formatting characters, and end in a
character that selects the field of the struct stat which is to be
formatted. If the % is immediately followed by one of n, t, %, or @, then
a newline character, a tab character, a percent character, or the current
file number is printed, otherwise the string is examined for the following:
Any of the following optional flags:
# Selects an alternate output form for octal and hexadecimal output.
Non-zero octal output will have a leading zero, and non-zero
hexadecimal output will have “0x” prepended to it.
+ Asserts that a sign indicating whether a number is positive or
negative should always be printed. Non-negative numbers are not
usually printed with a sign.
- Aligns string output to the left of the field, instead of to the
right.
0 Sets the fill character for left padding to the ‘0’ character,
instead of a space.
space Reserves a space at the front of non-negative signed output fields.
A ‘+’ overrides a space if both are used.
Then the following fields:
size An optional decimal digit string specifying the minimum field
width.
prec An optional precision composed of a decimal point ‘.’ and a decimal
digit string that indicates the maximum string length, the number
of digits to appear after the decimal point in floating point
output, or the minimum number of digits to appear in numeric
output.
fmt An optional output format specifier which is one of D, O, U, X, F,
or S. These represent signed decimal output, octal output,
unsigned decimal output, hexadecimal output, floating point output,
and string output, respectively. Some output formats do not apply
to all fields. Floating point output only applies to timespec
fields (the a, m, and c fields).
The special output specifier S may be used to indicate that the
output, if applicable, should be in string format. May be used in
combination with:
amc Display date in strftime(3) format.
dr Display actual device name.
f Display the flags of file as in ls -lTdo.
gu Display group or user name.
p Display the mode of file as in ls -lTd.
N Displays the name of file.
T Displays the type of file.
Y Insert a “ -> ” into the output. Note that the default
output format for Y is a string, but if specified
explicitly, these four characters are prepended.
sub An optional sub field specifier (high, middle, low). Only applies
to the p, d, r, and T output formats. It can be one of the
following:
H “High” — specifies the major number for devices from r or
d, the “user” bits for permissions from the string form of
p, the file “type” bits from the numeric forms of p, and
the long output form of T.
L “Low” — specifies the minor number for devices from r or d,
the “other” bits for permissions from the string form of p,
the “user”, “group”, and “other” bits from the numeric
forms of p, and the ls -F style output character for file
type when used with T (the use of L for this is optional).
M “Middle” — specifies the “group” bits for permissions from
the string output form of p, or the “suid”, “sgid”, and
“sticky” bits for the numeric forms of p.
datum A required field specifier, being one of the following:
d Device upon which file resides (st_dev).
i file's inode number (st_ino).
p File type and permissions (st_mode).
l Number of hard links to file (st_nlink).
u, g User ID and group ID of file's owner (st_uid, st_gid).
r Device number for character and block device special files
(st_rdev).
a, m, c, B
The time file was last accessed or modified, or when the
inode was last changed, or the birth time of the inode
(st_atime, st_mtime, st_ctime, st_birthtime).
z The size of file in bytes (st_size).
b Number of blocks allocated for file (st_blocks).
k Optimal file system I/O operation block size (st_blksize).
f User defined flags for file.
v Inode generation number (st_gen).
The following five field specifiers are not drawn directly from the
data in struct stat, but are:
N The name of the file.
R The absolute pathname corresponding to the file.
T The file type, either as in ls -F or in a more descriptive
form if the sub field specifier H is given.
Y The target of a symbolic link.
Z Expands to “major,minor” from the rdev field for character
or block special devices and gives size output for all
others.
Only the % and the field specifier are required. Most field specifiers
default to U as an output form, with the exception of p which defaults to
O; a, m, and c which default to D; and Y, T, and N which default to S.
EXIT STATUS
The stat and readlink utilities exit 0 on success, and >0 if an error
occurs.
EXAMPLES
If no options are specified, the default format is "%d %i %Sp %l %Su %Sg %r
%z \"%Sa\" \"%Sm\" \"%Sc\" \"%SB\" %k %b %#Xf %N".
> stat /tmp/bar
0 78852 -rw-r--r-- 1 root wheel 0 0 "Jul 8 10:26:03 2004" "Jul 8 10:26:03 2004" "Jul 8 10:28:13 2004" "Jan 1 09:00:00 1970" 16384 0 0 /tmp/bar
Given a symbolic link “foo” that points from /tmp/foo to /, you would use
stat as follows:
> stat -F /tmp/foo
lrwxrwxrwx 1 jschauma cs 1 Apr 24 16:37:28 2002 /tmp/foo@ -> /
> stat -LF /tmp/foo
drwxr-xr-x 16 root wheel 512 Apr 19 10:57:54 2002 /tmp/foo/
To initialize some shell variables, you could use the -s flag as follows:
> csh
% eval set `stat -s .cshrc`
% echo $st_size $st_mtimespec
1148 1015432481
> sh
$ eval $(stat -s .profile)
$ echo $st_size $st_mtimespec
1148 1015432481
In order to get a list of file types including files pointed to if the file
is a symbolic link, you could use the following format:
$ stat -f "%N: %HT%SY" /tmp/*
/tmp/bar: Symbolic Link -> /tmp/foo
/tmp/output25568: Regular File
/tmp/blah: Directory
/tmp/foo: Symbolic Link -> /
In order to get a list of the devices, their types and the major and minor
device numbers, formatted with tabs and linebreaks, you could use the
following format:
stat -f "Name: %N%n%tType: %HT%n%tMajor: %Hr%n%tMinor: %Lr%n%n" /dev/*
[...]
Name: /dev/wt8
Type: Block Device
Major: 3
Minor: 8
Name: /dev/zero
Type: Character Device
Major: 2
Minor: 12
In order to determine the permissions set on a file separately, you could
use the following format:
> stat -f "%Sp -> owner=%SHp group=%SMp other=%SLp" .
drwxr-xr-x -> owner=rwx group=r-x other=r-x
In order to determine the three files that have been modified most
recently, you could use the following format:
> stat -f "%m%t%Sm %N" /tmp/* | sort -rn | head -3 | cut -f2-
Apr 25 11:47:00 2002 /tmp/blah
Apr 25 10:36:34 2002 /tmp/bar
Apr 24 16:47:35 2002 /tmp/foo
To display a file's modification time:
> stat -f %m /tmp/foo
1177697733
To display the same modification time in a readable format:
> stat -f %Sm /tmp/foo
Apr 27 11:15:33 2007
To display the same modification time in a readable and sortable format:
> stat -f %Sm -t %Y%m%d%H%M%S /tmp/foo
20070427111533
To display the same in UTC:
> sh
$ TZ= stat -f %Sm -t %Y%m%d%H%M%S /tmp/foo
20070427181533
SEE ALSO
file(1), ls(1), lstat(2), readlink(2), stat(2), printf(3), strftime(3)
HISTORY
The stat utility appeared in NetBSD 1.6 and FreeBSD 4.10.
AUTHORS
The stat utility was written by Andrew Brown <atatat@NetBSD.org>. This man
page was written by Jan Schaumann <jschauma@NetBSD.org>.
macOS 12.4 June 22, 2017 macOS 12.4
mathieu-lemay
LangLangBart
description
readlink: illegal optionGIF
course of action
Maybe add a note for macOS users.