Had never thought of building such a tool, but now that you mention it, there were cases where I had Unix sitmestamps in log/debug files for instance. I ended up using the web browser console to do a quick conversion.
I just gave it a try now, as a shell script:
#!/bin/sh
# https://news.ycombinator.com/item?id=31233092
case "$1" in
-*|"")
echo "Usage: datez <unix-timestamp>"
;;
*)
if date -r "$1" 2>/dev/null; then date -r "$1"; else date -d "@$1"; fi
esac
Edit: tried to add the reverse, from human-readable-timestamp to Unix timestamp, and got a problem when the locale does not use the English language: the human-readable form is not understood by
date as input!
So the round-tripping version of the script has to set the locale to C:
#!/bin/sh
# https://news.ycombinator.com/item?id=31233092
# Needed for round-tripping:
export LANG=C
case "${1}" in
-*|"")
echo "Usage: datez <unix-timestamp|human-readable-timestamp>"
;;
*)
case "${1}" in
(*[!0-9]*)
date -d "${1}" +"%s"
;;
(*)
if date -r "${1}" 2>/dev/null; then
date -r "${1}"
else
date -d "@${1}"
fi
esac
esac
Edit 2: it does round-trip by using a locale-independent format like
"%Y-%m-%d %H:%M:%S %Z", which is anyhow the format I prefer:
#!/bin/sh
# https://news.ycombinator.com/item?id=31233092
# Needed for round-tripping if you use a locale-dependant format:
#export LANG=C
FORMAT="%Y-%m-%d %H:%M:%S %Z"
case "${1}" in
-*|"")
echo "Usage: datez <unix-timestamp|human-readable-timestamp>"
;;
*)
case "${1}" in
(*[!0-9]*)
date -d "${1}" +"%s"
;;
(*)
if date -r "${1}" 2>/dev/null; then
date -r "${1}" +"'${FORMAT}'"
else
date -d "@${1}" +"'${FORMAT}'"
fi
esac
esac