[dbohdan] 2017-08-23: `now` is a little date and time calculator utility for the command line. It leverages Tcl's `[clock add]` for date arithmetic. Download with [wiki-reaper]: `wiki-reaper -x 48963 1 | tee now.tcl` ** Use examples ** ======none $ now Wed Aug 23 19:46:15 DST 2017 $ now -3491 days Fri Feb 01 19:46:37 STD 2008 $ now -timezone :UTC -9 years -6 months -22 days +5 hours 5 minutes Fri Feb 01 22:54:59 UTC 2008 ====== ** Code ** ====== #! /usr/bin/env tclsh # now v0.4.0 copyright (c) 2017-2018, 2021 D. Bohdan. License: MIT. package require Tcl 8.5-10 proc usage {} { puts stderr [format {usage: %s [-format fmt] [-gmt 0/1] [-locale loc]\ [-timezone tz] [count unit ...]} \ [file tail [info script]]] } # Parse the command line options. Give an informative message on error. proc parse opts { set formatOpts {} while {[llength $opts] > 0 && ![string is integer -strict [lindex $opts 0]]} { set opts [lassign $opts k v] switch -exact -- $k { -h - --help { return -code 1 -errorcode {PARSE usage} } -format - -gmt - -locale - -timezone { lappend formatOpts $k $v } default { return -code 1 -errorcode {PARSE unknownOption} \ "unknown option \"$k\"" } } } set delta {} foreach {count unit} $opts { set units { y year m month d day h hour min minute s second } if {![string is integer -strict $count]} { return -code 1 "expected integer count, but got \"$count\"" } set unit [string tolower $unit] # Strip "s" at the end, but only if $unit isn't just "s". regexp ^(.+?)s?$ $unit _ unit # Expand abbreviations. if {[dict exists $units $unit]} { set unit [dict get $units $unit] } if {$unit eq {}} { error "no unit given for count $count" } elseif {$unit ni [dict values $units]} { error [format {unknown unit "%s", must be "year" ("y"),\ "month" ("m"), "day" ("d"), "hour" ("h"),\ "minute" ("min") or "second" ("s") with an optional\ suffix "-s"} \ $unit] } lappend delta $count $unit } return [list $formatOpts $delta] } # Output the date and time. if {[catch { lassign [parse $argv] formatOpts delta puts [clock format [clock add [clock seconds] {*}$delta] {*}$formatOpts] } res errOpts]} { set ec [dict get $errOpts -errorcode] if {$ec eq {PARSE usage}} { usage exit 0 } else { puts stderr "error: $res" if {$ec eq {PARSE unknownOption}} { usage } exit 1 } } ====== <> Application | Date and Time