Question

I inherited a TCL script (I have zero familiarity with the language) and need to add an RFC 3339 timestamp to it:

2012-04-05T12:13:32.123456-08:00

After searching Google, I haven’t found any means of displaying the microseconds or the timezone offset (I have found a way to show the timezone name, but that doesn’t help).
Is there a way to do this without calling an external process?

Answer 1

In TCL8.5, you can try the following command:

% clock format [clock seconds] -format "%Y-%m-%dT%T%z"
2012-04-05T16:06:07-0500

That gives you everything except the sub-second resolution. The clock microseconds command will give you the time in microseconds, but I can’t find a format string identifier that matches it. You can use this to build your own command from scratch:

proc timestamp_rfc3339 {} {
    set us [clock microseconds]
    set sec [expr {$us / 1000000}]
    set micro [expr {$us % 1000000}]
    set ts [clock format $sec -format "%Y-%m-%dT%T"]
    regexp {(...)(..)} [clock format $sec -format "%z"] matched tzh tzm
    return [format "%s.%06s%s:%s" $ts $micro $tzh $tzm]
}

Running this results in a timestamp like 2012-04-05T16:35:06.366378-05:00.

Edit: Updated code sample to incorporate user1179884’s tweaks (see comments) and to wrap in a proc.