[git] How to change Git log date formats

I am trying to display the last commit within Git, but I need the date in a special format.

I know that the log pretty format %ad respects the --date format, but the only --date format I can find is "short". I want to know the others, and whether I can create a custom one such as:

git -n 1 --date=**YYMMDDHHmm** --pretty=format:"Last committed item in this release was by %%an, %%aD, message: %%s(%%h)[%%d]"

After a long time looking for a way to get git log output the date in the format YYYY-MM-DD in a way that would work in less, I came up with the following format:

%ad%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08

along with the switch --date=iso.

This will print the date in ISO format (a long one), and then print 14 times the backspace character (0x08), which, in my terminal, effectively removes everything after the YYYY-MM-DD part. For example:

git log --date=iso --pretty=format:'%ad%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%aN %s'

This gives something like:

2013-05-24 bruno This is the message of the latest commit.
2013-05-22 bruno This is an older commit.
...

What I did was create an alias named l with some tweaks on the format above. It shows the commit graph to the left, then the commit's hash, followed by the date, the shortnames, the refnames and the subject. The alias is as follows (in ~/.gitconfig):

[alias]
        l = log --date-order --date=iso --graph --full-history --all --pretty=format:'%x08%x09%C(red)%h %C(cyan)%ad%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08 %C(bold blue)%aN%C(reset)%C(bold yellow)%d %C(reset)%s'

In addition to --date=(relative|local|default|iso|iso-strict|rfc|short|raw), as others have mentioned, you can also use a custom log date format with

--date=format:'%Y-%m-%d %H:%M:%S'

This outputs something like 2016-01-13 11:32:13.

NOTE: If you take a look at the commit linked to below, I believe you'll need at least Git v2.6.0-rc0 for this to work.

In a full command it would be something like:

git config --global alias.lg "log --graph --decorate 
-30 --all --date-order --date=format:'%Y-%m-%d %H:%M:%S' 
--pretty=format:'%C(cyan)%h%Creset %C(black bold)%ad%Creset%C(auto)%d %s'" 

I haven't been able to find this in documentation anywhere (if someone knows where to find it, please comment) so I originally found the placeholders by trial and error.

In my search for documentation on this I found a commit to Git itself that indicates the format is fed directly to strftime. Looking up strftime (here or here) the placeholders I found match the placeholders listed.

The placeholders include:

%a      Abbreviated weekday name
%A      Full weekday name
%b      Abbreviated month name
%B      Full month name
%c      Date and time representation appropriate for locale
%d      Day of month as decimal number (01 – 31)
%H      Hour in 24-hour format (00 – 23)
%I      Hour in 12-hour format (01 – 12)
%j      Day of year as decimal number (001 – 366)
%m      Month as decimal number (01 – 12)
%M      Minute as decimal number (00 – 59)
%p      Current locale's A.M./P.M. indicator for 12-hour clock
%S      Second as decimal number (00 – 59)
%U      Week of year as decimal number, with Sunday as first day of week (00 – 53)
%w      Weekday as decimal number (0 – 6; Sunday is 0)
%W      Week of year as decimal number, with Monday as first day of week (00 – 53)
%x      Date representation for current locale
%X      Time representation for current locale
%y      Year without century, as decimal number (00 – 99)
%Y      Year with century, as decimal number
%z, %Z  Either the time-zone name or time zone abbreviation, depending on registry settings
%%      Percent sign

In a full command it would be something like

git config --global alias.lg "log --graph --decorate -30 --all --date-order --date=format:'%Y-%m-%d %H:%M:%S' --pretty=format:'%C(cyan)%h%Creset %C(black bold)%ad%Creset%C(auto)%d %s'" 

The format option %ai was what I wanted:

%ai: author date, ISO 8601-like format

--format="%ai"

date -d @$(git log -n1 --format="%at") +%Y%m%d%H%M

Note that this will convert to your local timezone, in case that matters for your use case.

I need the date in a special format.

With Git 2.21 (Q1 2019), a new date format "--date=human" that morphs its output depending on how far the time is from the current time has been introduced.

"--date=auto" can be used to use this new format when the output is going to the pager or to the terminal and otherwise the default format.

See commit 110a6a1, commit b841d4f (29 Jan 2019), and commit 038a878, commit 2fd7c22 (21 Jan 2019) by Stephen P. Smith (``).
See commit acdd377 (18 Jan 2019) by Linus Torvalds (torvalds).
^{(Merged by Junio C Hamano -- gitster -- in commit ecbe1be, 07 Feb 2019)}

Add 'human' date format documentation

Display date and time information in a format similar to how people write dates in other contexts.
If the year isn't specified then, the reader infers the date is given is in the current year.

By not displaying the redundant information, the reader concentrates on the information that is different.
The patch reports relative dates based on information inferred from the date on the machine running the git command at the time the command is executed.

While the format is more useful to humans by dropping inferred information, there is nothing that makes it actually human.
If the 'relative' date format wasn't already implemented, then using 'relative' would have been appropriate.

Add human date format tests.

When using human several fields are suppressed depending on the time difference between the reference date and the local computer date.

• In cases where the difference is less than a year, the year field is suppressed.
• If the time is less than a day; the month and year is suppressed.

check_date_format_human 18000       "5 hours ago"       #  5 hours ago
check_date_format_human 432000      "Tue Aug 25 19:20"  #  5 days ago
check_date_format_human 1728000     "Mon Aug 10 19:20"  #  3 weeks ago
check_date_format_human 13000000    "Thu Apr 2 08:13"   #  5 months ago
check_date_format_human 31449600    "Aug 31 2008"       # 12 months ago
check_date_format_human 37500000    "Jun 22 2008"       #  1 year, 2 months ago
check_date_format_human 55188000    "Dec 1 2007"        #  1 year, 9 months ago
check_date_format_human 630000000   "Sep 13 1989"       # 20 years ago

## Replace the proposed 'auto' mode with 'auto:'

In addition to adding the 'human' format, the patch added the auto keyword which could be used in the config file as an alternate way to specify the human format. Removing 'auto' cleans up the 'human' format interface.

Added the ability to specify mode 'foo' if the pager is being used by using auto:foo syntax.
Therefore, 'auto:human' date mode defaults to human if we're using the pager.
So you can do:

git config --add log.date auto:human

and your "git log" commands will show the human-legible format unless you're scripting things.

Git 2.24 (Q4 2019) simplified the code.

See commit 47b27c9, commit 29f4332 (12 Sep 2019) by Stephen P. Smith (``).
^{(Merged by Junio C Hamano -- gitster -- in commit 36d2fca, 07 Oct 2019)}

Quit passing 'now' to date code

Commit b841d4f (Add human format to test-tool, 2019-01-28, Git v2.21.0-rc0) added a get_time() function which allows $GIT_TEST_DATE_NOW in the environment to override the current time.
So we no longer need to interpret that variable in cmd__date().

Therefore, we can stop passing the "now" parameter down through the date functions, since nobody uses them.
Note that we do need to make sure all of the previous callers that took a "now" parameter are correctly using get_time().

Be aware of the "date=iso" format: it isn't exactly ISO 8601.
See commit "466fb67" from Beat Bolli (bbolli), for Git 2.2.0 (November 2014)

pretty: provide a strict ISO 8601 date format

Git's "ISO" date format does not really conform to the ISO 8601 standard due to small differences, and it cannot be parsed by ISO 8601-only parsers, e.g. those of XML toolchains.

The output from "--date=iso" deviates from ISO 8601 in these ways:

• a space instead of the T date/time delimiter
• a space between time and time zone
• no colon between hours and minutes of the time zone

Add a strict ISO 8601 date format for displaying committer and author dates.
Use the '%aI' and '%cI' format specifiers and add '--date=iso-strict' or '--date=iso8601-strict' date format names.

See this thread for discussion.

I needed the same thing and found the following working for me:

git log -n1 --pretty='format:%cd' --date=format:'%Y-%m-%d %H:%M:%S'

The --date=format formats the date output where the --pretty tells what to print.

Use Bash and the date command to convert from an ISO-like format to the one you want. I wanted an org-mode date format (and list item), so I did this:

echo + [$(date -d "$(git log --pretty=format:%ai -1)" +"%Y-%m-%d %a %H:%M")] \
    $(git log --pretty=format:"%h %s" --abbrev=12 -1)

And the result is for example:

+ [2015-09-13 Sun 22:44] 2b0ad02e6cec Merge pull request #72 from 3b/bug-1474631

git log -n1 --format="Last committed item in this release was by %an, `git log -n1 --format=%at | awk '{print strftime("%y%m%d%H%M",$1)}'`, message: %s (%h) [%d]"

Git 2.7 (Q4 2015) will introduce -local as an instruction.
It means that, in addition to:

--date=(relative|local|default|iso|iso-strict|rfc|short|raw)

you will also have:

--date=(default-local|iso-local|iso-strict-local|rfc-local|short-local)

The -local suffix cannot be used with raw or relative. Reference.

You now can ask for any date format using the local timezone. See

• commit 99264e9,
• commit db7bae2,
• commit dc6d782,
• commit f3c1ba5,
• commit f95cecf,
• commit 4b1c5e1,
• commit 8f50d26,
• commit 78a8441,
• commit 2df4e29 (03 Sep 2015) by John Keeping (johnkeeping).

See commit add00ba, commit 547ed71 (03 Sep 2015) by Jeff King (peff).
^{(Merged by Junio C Hamano -- gitster -- in commit 7b09c45, 05 Oct 2015)}

In particular, the last from above (commit add00ba) mentions:

date: make "local" orthogonal to date format:

Most of our "--date" modes are about the format of the date: which items we show and in what order.
But "--date=local" is a bit of an oddball. It means "show the date in the normal format, but using the local timezone".
The timezone we use is orthogonal to the actual format, and there is no reason we could not have "localized iso8601", etc.

This patch adds a "local" boolean field to "struct date_mode", and drops the DATE_LOCAL element from the date_mode_type enum (it's now just DATE_NORMAL plus local=1).
The new feature is accessible to users by adding "-local" to any date mode (e.g., "iso-local"), and we retain "local" as an alias for "default-local" for backwards compatibility.

You can use the field truncation option to avoid quite so many %x08 characters. For example:

git log --pretty='format:%h %s%n\t%<(12,trunc)%ci%x08%x08, %an <%ae>'

is equivalent to:

git log --pretty='format:%h %s%n\t%ci%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08%x08, %an <%ae>'

And quite a bit easier on the eyes.

Better still, for this particular example, using %cd will honor the --date=<format>, so if you want YYYY-MM-DD, you can do this and avoid %< and %x08 entirely:

git log --date=short --pretty='format:%h %s%n\t%cd, %an <%ae>'

I just noticed this was a bit circular with respect to the original post but I'll leave it in case others arrived here with the same search parameters I did.