Get the time and date of git tags

This always worked for me:

git log --tags --simplify-by-decoration --pretty="format:%ci %d"

Consult the "PRETTY FORMATS" section of the git-log manpage for details of the format string if you want a different date formatting.

One more option:

git for-each-ref --format="%(refname:short) | %(creatordate)" "refs/tags/*"

See https://git-scm.com/docs/git-for-each-ref#_field_names for format options

%(creatordate) gives the date of the commit pointed to, to see the date the tag was created on use %(taggerdate)

You can incorporate the shell directly:

$> git for-each-ref --shell --format="ref=%(refname:short) dt=%(taggerdate:format:%s)" "refs/tags/*"

ref='v1.10' dt='1483807817'
ref='v1.11' dt='1483905854'
ref='v1.12.0' dt='1483974797'
ref='v1.12.1' dt='1484015966'
ref='v1.13' dt='1484766542'
ref='v1.2' dt='1483414377'
ref='v1.3' dt='1483415058'
ref='v1.3-release' dt='' <-- not an annotated tag, just a pointer to a commit so no 'taggerdate', it would have a 'creator date'.
ref='v1.3.1' dt='1483487085'
ref='v1.4' dt='1483730146'
ref='v1.9' dt='1483802985'

Note that both of the above solutions get you the commit date, which can be wildly different than when that commit was tagged for release. To get the date of the tag itself, you've got to find the tag itself with rev-parse, read it with cat-file, and then parse it. A little pipeline:

git rev-parse v1.0.0 | xargs git cat-file -p | egrep '^tagger' | cut -f2 -d '>'

There is no simple option in git tag command to do this. I found most convenient to run

git log --decorate=full

to list all commits including tags if there are some. For listing only commits that are tagged use

git log --decorate=full --simplify-by-decoration

For details use

git help log

one can use gawk (not awk) to convert date in the "tagger" line to something human-readable:

git rev-parse v4.4-rc1 | xargs git cat-file -p | gawk '/^tagger/ { print strftime(PROCINFO["strftime"], $(NF-1)) }'

if one does not like gawk then date can be used to convert unix time:

git rev-parse v2.76 | xargs git cat-file -p | awk '/^tagger/ { print "@" $(NF-1) }' | xargs date -d

and example (dnsmasq git repo):

$ git rev-parse v2.76 | xargs git cat-file -p | awk '/^tagger/ { print "@" $(NF-1) }' | xargs date -d
Wed May 18 16:52:12 CEST 2016

All of the answers here are great and in the proper git style. But I needed a tag, its date and its message and only the last 10 tags. So I just did it in a very pedestrian way. But save it as a shell function or script and it becomes a one-liner.

for ver in `git tag | tail -10`; do
    DATE=`git log -1 --format=%ai $ver | awk '{print $1}'`
    MESSAGE=`git tag -n $ver | cat | awk '{a=match($0, $2); print substr($0,a)}'`
    echo "$ver \t| $DATE | $MESSAGE"
done

Answers above gave me wrong dates for my tag date, I don't know why, so here is what finally worked for me:

git tag --list "$MY_TAG_NAME" --format="%(taggerdate)"
Tue Oct 29 14:47:46 2024 +0100

You can also have the timestamp by doing this instead:

git tag --list "$MY_TAG_NAME" --format="%(taggerdate:unix)"
1730209666

I use this script which deletes tags with last commit over a year ago. Also, it assumes the "origin" name for the remote repository.

#!/bin/bash
# Timestamp one year ago - use whatever time stamp you you like
some_time_in_the_past=$(date --date="1 year ago" +%s)

# Gå through all tags
for tag in $(git tag); do
    # Get date for last commit in the annotated tag
    tag_date=$(git log -1 --format=%ct "$tag")
    if [ "$tag_date" -lt "$some_time_in_the_past" ]; then
        echo "Removing tag: $tag"
        # Remove tag locally
        git tag -d "$tag"
        # Remove tag from origin (classic method)
        # git push origin :refs/tags/"$tag"
        # Alternative method (newer Git-versions):
        git push --delete origin "$tag"
    fi
done