By default, file timestamps are listed in abbreviated form, using a date like ‘Mar 30 2002’ for non-recent timestamps, and a date-without-year and time like ‘Mar 30 23:45’ for recent timestamps. This format can change depending on the current locale as detailed below.
A timestamp is considered to be recent if it is less than six
months old, and is not dated in the future. If a timestamp dated
today is not listed in recent form, the timestamp is in the future,
which means you probably have clock skew problems which may break
make that rely on file timestamps.
Time stamps are listed according to the time zone rules specified by
TZ environment variable, or by the system default rules if
TZ is not set. See Specifying the Time Zone
TZ in The GNU C Library Reference Manual.
The following option changes how file timestamps are printed.
List timestamps in style style. The style should be one of the following:
List timestamps using format, where format is interpreted
like the format argument of
date (see date invocation).
For example, --time-style="+%Y-%m-%d %H:%M:%S" causes
ls to list timestamps like ‘2002-03-30 23:45:56’. As
date, format’s interpretation is affected by the
LC_TIME locale category.
If format contains two format strings separated by a newline, the former is used for non-recent files and the latter for recent files; if you want output columns to line up, you may need to insert spaces in one of the two formats.
List timestamps in full using ISO 8601 date, time, and time zone components with nanosecond precision, e.g., ‘2002-03-30 23:45:56.477817180 -0700’. This style is equivalent to ‘+%Y-%m-%d %H:%M:%S.%N %z’.
This is useful because the time output includes all the information that
is available from the operating system. For example, this can help
make’s behavior, since GNU
uses the full timestamp to determine whether a file is out of date.
List ISO 8601 date and time components with minute precision, e.g., ‘2002-03-30 23:45’. These timestamps are shorter than ‘full-iso’ timestamps, and are usually good enough for everyday work. This style is equivalent to ‘+%Y-%m-%d %H:%M’.
List ISO 8601 dates for non-recent timestamps (e.g.,
‘2002-03-30 ’), and ISO 8601-like month, day, hour, and
minute for recent timestamps (e.g., ‘03-30 23:45’). These
timestamps are uglier than ‘long-iso’ timestamps, but they carry
nearly the same information in a smaller space and their brevity helps
ls output fit within traditional 80-column output lines.
The following two
ls invocations are equivalent:
newline=' ' ls -l --time-style="+%Y-%m-%d $newline%m-%d %H:%M" ls -l --time-style="iso"
List timestamps in a locale-dependent form. For example, a Finnish locale might list non-recent timestamps like ‘maalis 30 2002’ and recent timestamps like ‘maalis 30 23:45’. Locale-dependent timestamps typically consume more space than ‘iso’ timestamps and are harder for programs to parse because locale conventions vary so widely, but they are easier for many people to read.
LC_TIME locale category specifies the timestamp format. The
default POSIX locale uses timestamps like ‘Mar 30 2002’ and ‘Mar 30 23:45’; in this locale, the following two
ls invocations are equivalent:
newline=' ' ls -l --time-style="+%b %e %Y$newline%b %e %H:%M" ls -l --time-style="locale"
Other locales behave differently. For example, in a German locale, --time-style="locale" might be equivalent to --time-style="+%e. %b %Y $newline%e. %b %H:%M" and might generate timestamps like ‘30. Mär 2002 ’ and ‘30. Mär 23:45’.
List POSIX-locale timestamps if the
category is POSIX, style timestamps otherwise. For
example, the ‘posix-long-iso’ style lists
timestamps like ‘Mar 30 2002’ and ‘Mar 30 23:45’ when in
the POSIX locale, and like ‘2002-03-30 23:45’ otherwise.
You can specify the default value of the --time-style option
with the environment variable
TIME_STYLE is not set
the default style is ‘locale’. GNU Emacs 21.3 and
later use the --dired option and therefore can parse any date
format, but if you are using Emacs 21.1 or 21.2 and specify a
non-POSIX locale you may need to set
To avoid certain denial-of-service attacks, timestamps that would be longer than 1000 bytes may be treated as errors.