看了一下，ubuntu 的 man ls 确实不够详细。贴一个 BSD 的：
你的答案在 The Long Format 一节。
LS(1) BSD General Commands Manual LS(1)
ls -- list directory contents
ls [-ABCFGHLPRSTW@abcdefghiklmnopqrstuwx1] [file ...]
For each operand that names a file of a type other than directory, ls
displays its name as well as any requested, associated information. For
each operand that names a file of type directory, ls displays the names
of files contained within that directory, as well as any requested, asso-
If no operands are given, the contents of the current directory are dis-
played. If more than one operand is given, non-directory operands are
displayed first; directory and non-directory operands are sorted sepa-
rately and in lexicographical order.
The following options are available:
-@ Display extended attribute keys and sizes.
-1 (The numeric digit ``one''.) Force output to be one entry per
line. This is the default when output is not to a terminal.
-A List all entries except for . and ... Always set for the super-
-a Include directory entries whose names begin with a dot (.).
-B Force printing of non-printable characters (as defined by
ctype(3) and current locale settings) in file names as \xxx,
where xxx is the numeric value of the character in octal.
-b As -B, but use C escape codes whenever possible.
-C Force multi-column output; this is the default when output is to
-c Use time when file status was last changed for sorting or print-
-d Directories are listed as plain files (not searched recursively).
-e Print the Access Control List (ACL) associated with the file, if
-F 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, an equals sign (`=') after
each socket, a percent sign (`%') after each whiteout, and a ver-
tical bar (`|') after each that is a FIFO.
-f Output is not sorted. This option turns on the -a option.
-G Enable colorized output. This option is equivalent to defining
CLICOLOR in the environment. (See below.)
-g This option is only available for compatibility with POSIX; it is
used to display the group name in the long (-l) format output
(the owner name is suppressed).
-H Symbolic links on the command line are followed. This option is
assumed if none of the -F, -d, or -l options are specified.
-h When used with the -l option, use unit suffixes: Byte, Kilobyte,
Megabyte, Gigabyte, Terabyte and Petabyte in order to reduce the
number of digits to three or less using base 2 for sizes.
-i For each file, print the file's file serial number (inode num-
-k If the -s option is specified, print the file size allocation in
kilobytes, not blocks. This option overrides the environment
-L If argument is a symbolic link, list the file or directory the
link references rather than the link itself. This option cancels
the -P option.
-l (The lowercase letter ``ell''.) List in long format. (See
below.) If the output is to a terminal, a total sum for all the
file sizes is output on a line before the long listing.
-m Stream output format; list files across the page, separated by
-n Display user and group IDs numerically, rather than converting to
a user or group name in a long (-l) output. This option turns on
the -l option.
-O Include the file flags in a long (-l) output.
-o List in long format, but omit the group id.
-P If argument is a symbolic link, list the link itself rather than
the object the link references. This option cancels the -H and
-p Write a slash (`/') after each filename if that file is a direc-
-q Force printing of non-graphic characters in file names as the
character `?'; this is the default when output is to a terminal.
-R Recursively list subdirectories encountered.
-r Reverse the order of the sort to get reverse lexicographical
order or the oldest entries first (or largest files last, if com-
bined with sort by size
-S Sort files by size
-s Display the number of file system blocks actually used by each
file, in units of 512 bytes, where partial units are rounded up
to the next integer value. If the output is to a terminal, a
total sum for all the file sizes is output on a line before the
listing. The environment variable BLOCKSIZE overrides the unit
size of 512 bytes.
-T When used with the -l (lowercase letter ``ell'') option, display
complete time information for the file, including month, day,
hour, minute, second, and year.
-t Sort by time modified (most recently modified first) before sort-
ing the operands by lexicographical order.
-u Use time of last access, instead of last modification of the file
for sorting (-t) or printing (-l).
-v Force unedited printing of non-graphic characters; this is the
default when output is not to a terminal.
-W Display whiteouts when scanning directories. (-S) flag).
-w Force raw printing of non-printable characters. This is the
default when output is not to a terminal.
-x The same as -C, except that the multi-column output is produced
with entries sorted across, rather than down, the columns.
The -1, -C, -x, and -l options all override each other; the last one
specified determines the format used.
The -c and -u options override each other; the last one specified deter-
mines the file time used.
The -B, -b, -w, and -q options all override each other; the last one
specified determines the format used for non-printable characters.
The -H, -L and -P options all override each other (either partially or
fully); they are applied in the order specified.
By default, ls lists one entry per line to standard output; the excep-
tions are to terminals or when the -C or -x options are specified.
File information is displayed with one or more <blank>s separating the
information associated with the -i, -s, and -l options.
The Long Format
If the -l option is given, the following information is displayed for
each file: file mode, number of links, owner name, group name, number of
bytes in the file, abbreviated month, day-of-month file was last modi-
fied, hour file last modified, minute file last modified, and the path-
name. In addition, for each directory whose contents are displayed, the
total number of 512-byte blocks used by the files in the directory is
displayed on a line by itself, immediately before the information for the
files in the directory. If the file or directory has extended
attributes, the permissions field printed by the -l option is followed by
a '@' character. Otherwise, if the file or directory has extended secu-
rity information, the permissions field printed by the -l option is fol-
lowed by a '+' character.
If the modification time of the file is more than 6 months in the past or
future, then the year of the last modification is displayed in place of
the hour and minute fields.
If the owner or group names are not a known user or group name, or the -n
option is given, the numeric ID's are displayed.
If the file is a character special or block special file, the major and
minor device numbers for the file are displayed in the size field. If
the file is a symbolic link, the pathname of the linked-to file is pre-
ceded by ``->''.
The file mode printed under the -l option consists of the entry type,
owner permissions, and group permissions. The entry type character
describes the type of file, as follows:
b Block special file.
c Character special file.
l Symbolic link.
s Socket link.
- Regular file.
The next three fields are three characters each: owner permissions, group
permissions, and other permissions. Each field has three character posi-
1. If r, the file is readable; if -, it is not readable.
2. If w, the file is writable; if -, it is not writable.
3. The first of the following that applies:
S If in the owner permissions, the file is not exe-
cutable and set-user-ID mode is set. If in the
group permissions, the file is not executable and
set-group-ID mode is set.
s If in the owner permissions, the file is exe-
cutable and set-user-ID mode is set. If in the
group permissions, the file is executable and set-
group-ID mode is set.
x The file is executable or the directory is search-
- The file is neither readable, writable, exe-
cutable, nor set-user-ID nor set-group-ID mode,
nor sticky. (See below.)
These next two apply only to the third character in the last
group (other permissions).
T The sticky bit is set (mode 1000), but not execute
or search permission. (See chmod(1) or
t The sticky bit is set (mode 1000), and is search-
able or executable. (See chmod(1) or sticky(8).)
The following is how to do an ls listing sorted by increasing size
The ls utility exits 0 on success, and >0 if an error occurs.
The following environment variables affect the execution of ls:
BLOCKSIZE If the environment variable BLOCKSIZE is set, the block
counts (see -s) will be displayed in units of that size
CLICOLOR Use ANSI color sequences to distinguish file types. See
LSCOLORS below. In addition to the file types mentioned
in the -F option some extra attributes (setuid bit set,
etc.) are also displayed. The colorization is dependent
on a terminal type with the proper termcap(5) capabili-
ties. The default ``cons25'' console has the proper
capabilities, but to display the colors in an xterm(1),
for example, the TERM variable must be set to
``xterm-color''. Other terminal types may require simi-
lar adjustments. Colorization is silently disabled if
the output isn't directed to a terminal unless the
CLICOLOR_FORCE variable is defined.
CLICOLOR_FORCE Color sequences are normally disabled if the output isn't
directed to a terminal. This can be overridden by set-
ting this flag. The TERM variable still needs to refer-
ence a color capable terminal however otherwise it is not
possible to determine which color sequences to use.
COLUMNS If this variable contains a string representing a decimal
integer, it is used as the column position width for dis-
playing multiple-text-column output. The ls utility cal-
culates how many pathname text columns to display based
on the width provided. (See -C and -x.)
LANG The locale to use when determining the order of day and
month in the long -l format output. See environ(7) for
LSCOLORS The value of this variable describes what color to use
for which attribute when colors are enabled with
CLICOLOR. This string is a concatenation of pairs of the
format fb, where f is the foreground color and b is the
The color designators are as follows:
h light grey
A bold black, usually shows up as dark grey
B bold red
C bold green
D bold brown, usually shows up as yellow
E bold blue
F bold magenta
G bold cyan
H bold light grey; looks like bright white
x default foreground or background
Note that the above are standard ANSI colors. The actual
display may differ depending on the color capabilities of
the terminal in use.
The order of the attributes are as follows:
2. symbolic link
6. block special
7. character special
8. executable with setuid bit set
9. executable with setgid bit set
10. directory writable to others, with sticky bit
11. directory writable to others, without sticky
The default is "exfxcxdxbxegedabagacad", i.e. blue fore-
ground and default background for regular directories,
black foreground and red background for setuid executa-
LS_COLWIDTHS If this variable is set, it is considered to be a colon-
delimited list of minimum column widths. Unreasonable
and insufficient widths are ignored (thus zero signifies
a dynamically sized column). Not all columns have
changeable widths. The fields are, in order: inode,
block count, number of links, user name, group name,
flags, file size, file name.
TERM The CLICOLOR functionality depends on a terminal type
with color capabilities.
TZ The timezone to use when displaying dates. See
environ(7) for more information.
The group field is now automatically included in the long listing for
files in order to be compatible with the IEEE Std 1003.2 (``POSIX.2'')
In legacy mode, the -f option does not turn on the -a option and the -g,
-n, and -o options do not turn on the -l option.
Also, the -o option causes the file flags to be included in a long (-l)
output; there is no -O option.
When -H is specified (and not overridden by -L or -P) and a file argument
is a symlink that resolves to a non-directory file, the output will
reflect the nature of the link, rather than that of the file. In legacy
operation, the output will describe the file.
chflags(1), chmod(1), sort(1), xterm(1), compat(5), termcap(5),
The ls utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
An ls command appeared in Version 1 AT&T UNIX.
To maintain backward compatibility, the relationships between the many
options are quite complex.
BSD May 19, 2002 BSD