lib/mdate-sh - automake - Git at Google

 #!/bin/sh
 # Get modification time of a file or directory, or value of
 # $SOURCE_DATE_EPOCH, and pretty-print it, formatted like 1 January 2000.

 scriptversion=2025-06-18.21; # UTC

 # Copyright (C) 1995-2025 Free Software Foundation, Inc.
 # written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, June 1995
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 2, or (at your option)
 # any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.

 # As a special exception to the GNU General Public License, if you
 # distribute this file as part of a program that contains a
 # configuration script generated by Autoconf, you may include it under
 # the same distribution terms that you use for the rest of that program.

 # This file is maintained in Automake, please report
 # bugs to <bug-automake@gnu.org> or send patches to
 # <automake-patches@gnu.org>.

 if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then
   emulate sh
   NULLCMD=:
   # Pre-4.2 versions of Zsh do word splitting on ${1+"$@"}, which
   # is contrary to our usage.  Disable this feature.
   alias -g '${1+"$@"}'='"$@"'
   setopt NO_GLOB_SUBST
 fi

 case $1 in
   '')
      echo "$0: No file.  Try '$0 --help' for more information." 1>&2
      exit 1;
      ;;
   -h | --h*)
     cat <<\EOF
 Usage: mdate-sh [--help] [--version] FILE

 Pretty-print the modification day of FILE, in the format:
 1 January 1970

 If the environment variable SOURCE_DATE_EPOCH is set, use its value (in
 epoch-seconds) for the date instead of any FILE mtime.  The FILE
 argument is still required in this case, but ignored.

 Report bugs to <bug-automake@gnu.org>.
 GNU Automake home page: <https://www.gnu.org/software/automake/>.
 General help using GNU software: <https://www.gnu.org/gethelp/>.
 EOF
     exit $?
     ;;
   -v | --v*)
     echo "mdate-sh (GNU Automake) $scriptversion"
     exit $?
     ;;
 esac

 # Warn if more than one file given.
 if test $# -ne 1; then
   echo "$0: warning: multiple files given, using first: $*" >&2
 fi

 error ()
 {
   echo "$0: $1" >&2
   exit 1
 }

 # set $month ("January") and $nummonth (1) given arg MON ("Jan").
 mon_to_month ()
 {
   case $1 in
     Jan) month=January; nummonth=1;;
     Feb) month=February; nummonth=2;;
     Mar) month=March; nummonth=3;;
     Apr) month=April; nummonth=4;;
     May) month=May; nummonth=5;;
     Jun) month=June; nummonth=6;;
     Jul) month=July; nummonth=7;;
     Aug) month=August; nummonth=8;;
     Sep) month=September; nummonth=9;;
     Oct) month=October; nummonth=10;;
     Nov) month=November; nummonth=11;;
     Dec) month=December; nummonth=12;;
   esac
 }

 # Prevent date giving response in another language.
 LANG=C
 export LANG
 LC_ALL=C
 export LC_ALL
 LC_TIME=C
 export LC_TIME

 # Use UTC to get reproducible result.
 TZ=UTC0
 export TZ

 #
 # https://reproducible-builds.org/docs/source-date-epoch/
 if test -n "$SOURCE_DATE_EPOCH"; then
   epoch_ok=true # be optimistic
   date_fmt="+%d %B %Y"
   result=`date -u --date="@$SOURCE_DATE_EPOCH" "$date_fmt" 2>/dev/null`
   if test -z "$result"; then
     result=`date -u -r "$SOURCE_DATE_EPOCH" "$date_fmt" 2>/dev/null`
     if test -z "$result"; then
       # The date command on Solaris 10 and 11 doesn't support any way
       # to do this. Fall back to Perl.
       #
       perlout=`perl -e 'print scalar gmtime($SOURCE_DATE_EPOCH)' 2>/dev/null`
       # Output is, e.g., Thu Jan  1 00:00:00 1970. Split it apart,
       # since we need to convert "Jan" to "January".
       # (We could use cut, but surely if a system has perl, it has awk?)
       day=`echo $perlout | awk '{print $3}'`
       mon=`echo $perlout | awk '{print $2}'`
       mon_to_month $mon # sets $month
       year=`echo $perlout | awk '{print $5}'`
       result="$day $month $year"
       #
       if test -z "$result"; then
         echo "$0: warning: SOURCE_DATE_EPOCH was set, but can't convert, ignoring: $SOURCE_DATE_EPOCH" >&2
         epoch_ok=false
       fi
     fi
   fi
   #
   if $epoch_ok; then
     # Remove leading spaces and zeros. We don't want to get into the
     # various date options to control this. (Not quoting $result here
     # isn't important, just another way to omit leading spaces.)
     result=`echo $result | sed 's/^[ 0]*//'`
     if test -z "$result"; then
       echo "$0: SOURCE_DATE_EPOCH was set, but converted to empty: $SOURCE_DATE_EPOCH" >&2
       epoch_ok=false
     fi
   fi
   if $epoch_ok; then
     echo $result
     exit 0
   else
     echo "$0: SOURCE_DATE_EPOCH failed, falling back to using mtime on: $1" >&2
   fi
 fi
 # end of SOURCE_DATE_EPOCH support, rest is about the normal case of
 # using the mtime of the specified file.

 #
 # GNU ls changes its time format in response to the TIME_STYLE
 # variable.  Since we cannot assume 'unset' works, revert this
 # variable to its documented default.
 if test "${TIME_STYLE+set}" = set; then
   TIME_STYLE=posix-long-iso
   export TIME_STYLE
 fi

 save_arg1=$1

 # Find out how to get the extended ls output of a file or directory.
 if ls -L /dev/null 1>/dev/null 2>&1; then
   ls_command='ls -L -l -d'
 else
   ls_command='ls -l -d'
 fi
 # Avoid user/group names that might have spaces, when possible.
 if ls -n /dev/null 1>/dev/null 2>&1; then
   ls_command="$ls_command -n"
 fi

 # A 'ls -l' line looks as follows on OS/2.
 #  drwxrwx---        0 Aug 11  2001 foo
 # This differs from Unix, which adds ownership information.
 #  drwxrwx---   2 root  root      4096 Aug 11  2001 foo
 #
 # To find the date, we split the line on spaces and iterate on words
 # until we find a month.  This cannot work with files whose owner is a
 # user named "Jan", or "Feb", etc.  However, it's unlikely that '/'
 # will be owned by a user whose name is a month.  So we first look at
 # the extended ls output of the root directory to decide how many
 # words should be skipped to get the date.

 # On HPUX /bin/sh, "set" interprets "-rw-r--r--" as options, so the "x" below.
 set x`$ls_command /`

 # Find which argument is the month.
 month=
 command=
 until test $month
 do
   test $# -gt 0 || error "failed parsing '$ls_command /' output"
   shift
   # Add another shift to the command.
   command="$command shift;"
   mon_to_month $1
 done

 test -n "$month" || error "failed parsing '$ls_command /' output"

 # Get the extended ls output of the file or directory.
 set dummy x`eval "$ls_command \"\\\$save_arg1\""`

 # Remove all preceding arguments
 eval $command

 # Because of the dummy argument above, month is in $2.
 #
 # On a POSIX system, we should have
 # $# = 5
 # $1 = file size
 # $2 = month
 # $3 = day
 # $4 = year or time
 # $5 = filename
 #
 # On Darwin 7.7.0 and 7.6.0, we have
 # $# = 4
 # $1 = day
 # $2 = month
 # $3 = year or time
 # $4 = filename

 # Get the month.
 mon_to_month $2

 case $3 in
   ???*) day=$1;;
   *) day=$3; shift;;
 esac

 # Here we have to deal with the problem that the ls output gives either
 # the time of day or the year.
 case $3 in
   *:*) set `date`; eval year=\$$#
        case $2 in
 	 Jan) nummonthtod=1;;
 	 Feb) nummonthtod=2;;
 	 Mar) nummonthtod=3;;
 	 Apr) nummonthtod=4;;
 	 May) nummonthtod=5;;
 	 Jun) nummonthtod=6;;
 	 Jul) nummonthtod=7;;
 	 Aug) nummonthtod=8;;
 	 Sep) nummonthtod=9;;
 	 Oct) nummonthtod=10;;
 	 Nov) nummonthtod=11;;
 	 Dec) nummonthtod=12;;
        esac
        # For the first six months of the year the time notation can also
        # be used for files modified in the last year.
        if (expr $nummonth \> $nummonthtod) >/dev/null;
        then
 	 year=`expr $year - 1`
        fi;;
   *) year=$3;;
 esac

 # The result.
 echo $day $month $year

 # Local Variables:
 # mode: shell-script
 # sh-indentation: 2
 # eval: (add-hook 'before-save-hook 'time-stamp nil t)
 # time-stamp-start: "scriptversion="
 # time-stamp-format: "%Y-%02m-%02d.%02H"
 # time-stamp-time-zone: "UTC0"
 # time-stamp-end: "; # UTC"
 # End:
	#!/bin/sh
	# Get modification time of a file or directory, or value of
	# $SOURCE_DATE_EPOCH, and pretty-print it, formatted like 1 January 2000.

	scriptversion=2025-06-18.21; # UTC

	# Copyright (C) 1995-2025 Free Software Foundation, Inc.
	# written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, June 1995
	#
	# This program is free software; you can redistribute it and/or modify
	# it under the terms of the GNU General Public License as published by
	# the Free Software Foundation; either version 2, or (at your option)
	# any later version.
	#
	# This program is distributed in the hope that it will be useful,
	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	# GNU General Public License for more details.
	#
	# You should have received a copy of the GNU General Public License
	# along with this program. If not, see <https://www.gnu.org/licenses/>.

	# As a special exception to the GNU General Public License, if you
	# distribute this file as part of a program that contains a
	# configuration script generated by Autoconf, you may include it under
	# the same distribution terms that you use for the rest of that program.

	# This file is maintained in Automake, please report
	# bugs to <bug-automake@gnu.org> or send patches to
	# <automake-patches@gnu.org>.

	if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then
	emulate sh
	NULLCMD=:
	# Pre-4.2 versions of Zsh do word splitting on ${1+"$@"}, which
	# is contrary to our usage. Disable this feature.
	alias -g '${1+"$@"}'='"$@"'
	setopt NO_GLOB_SUBST
	fi

	case $1 in
	'')
	echo "$0: No file. Try '$0 --help' for more information." 1>&2
	exit 1;
	;;
	-h \| --h*)
	cat <<\EOF
	Usage: mdate-sh [--help] [--version] FILE

	Pretty-print the modification day of FILE, in the format:
	1 January 1970

	If the environment variable SOURCE_DATE_EPOCH is set, use its value (in
	epoch-seconds) for the date instead of any FILE mtime. The FILE
	argument is still required in this case, but ignored.

	Report bugs to <bug-automake@gnu.org>.
	GNU Automake home page: <https://www.gnu.org/software/automake/>.
	General help using GNU software: <https://www.gnu.org/gethelp/>.
	EOF
	exit $?
	;;
	-v \| --v*)
	echo "mdate-sh (GNU Automake) $scriptversion"
	exit $?
	;;
	esac

	# Warn if more than one file given.
	if test $# -ne 1; then
	echo "$0: warning: multiple files given, using first: $*" >&2
	fi

	error ()
	{
	echo "$0: $1" >&2
	exit 1
	}

	# set $month ("January") and $nummonth (1) given arg MON ("Jan").
	mon_to_month ()
	{
	case $1 in
	Jan) month=January; nummonth=1;;
	Feb) month=February; nummonth=2;;
	Mar) month=March; nummonth=3;;
	Apr) month=April; nummonth=4;;
	May) month=May; nummonth=5;;
	Jun) month=June; nummonth=6;;
	Jul) month=July; nummonth=7;;
	Aug) month=August; nummonth=8;;
	Sep) month=September; nummonth=9;;
	Oct) month=October; nummonth=10;;
	Nov) month=November; nummonth=11;;
	Dec) month=December; nummonth=12;;
	esac
	}

	# Prevent date giving response in another language.
	LANG=C
	export LANG
	LC_ALL=C
	export LC_ALL
	LC_TIME=C
	export LC_TIME

	# Use UTC to get reproducible result.
	TZ=UTC0
	export TZ

	#
	# https://reproducible-builds.org/docs/source-date-epoch/
	if test -n "$SOURCE_DATE_EPOCH"; then
	epoch_ok=true # be optimistic
	date_fmt="+%d %B %Y"
	result=`date -u --date="@$SOURCE_DATE_EPOCH" "$date_fmt" 2>/dev/null`
	if test -z "$result"; then
	result=`date -u -r "$SOURCE_DATE_EPOCH" "$date_fmt" 2>/dev/null`
	if test -z "$result"; then
	# The date command on Solaris 10 and 11 doesn't support any way
	# to do this. Fall back to Perl.
	#
	perlout=`perl -e 'print scalar gmtime($SOURCE_DATE_EPOCH)' 2>/dev/null`
	# Output is, e.g., Thu Jan 1 00:00:00 1970. Split it apart,
	# since we need to convert "Jan" to "January".
	# (We could use cut, but surely if a system has perl, it has awk?)
	day=`echo $perlout \| awk '{print $3}'`
	mon=`echo $perlout \| awk '{print $2}'`
	mon_to_month $mon # sets $month
	year=`echo $perlout \| awk '{print $5}'`
	result="$day $month $year"
	#
	if test -z "$result"; then
	echo "$0: warning: SOURCE_DATE_EPOCH was set, but can't convert, ignoring: $SOURCE_DATE_EPOCH" >&2
	epoch_ok=false
	fi
	fi
	fi
	#
	if $epoch_ok; then
	# Remove leading spaces and zeros. We don't want to get into the
	# various date options to control this. (Not quoting $result here
	# isn't important, just another way to omit leading spaces.)
	result=`echo $result \| sed 's/^[ 0]*//'`
	if test -z "$result"; then
	echo "$0: SOURCE_DATE_EPOCH was set, but converted to empty: $SOURCE_DATE_EPOCH" >&2
	epoch_ok=false
	fi
	fi
	if $epoch_ok; then
	echo $result
	exit 0
	else
	echo "$0: SOURCE_DATE_EPOCH failed, falling back to using mtime on: $1" >&2
	fi
	fi
	# end of SOURCE_DATE_EPOCH support, rest is about the normal case of
	# using the mtime of the specified file.

	#
	# GNU ls changes its time format in response to the TIME_STYLE
	# variable. Since we cannot assume 'unset' works, revert this
	# variable to its documented default.
	if test "${TIME_STYLE+set}" = set; then
	TIME_STYLE=posix-long-iso
	export TIME_STYLE
	fi

	save_arg1=$1

	# Find out how to get the extended ls output of a file or directory.
	if ls -L /dev/null 1>/dev/null 2>&1; then
	ls_command='ls -L -l -d'
	else
	ls_command='ls -l -d'
	fi
	# Avoid user/group names that might have spaces, when possible.
	if ls -n /dev/null 1>/dev/null 2>&1; then
	ls_command="$ls_command -n"
	fi

	# A 'ls -l' line looks as follows on OS/2.
	# drwxrwx--- 0 Aug 11 2001 foo
	# This differs from Unix, which adds ownership information.
	# drwxrwx--- 2 root root 4096 Aug 11 2001 foo
	#
	# To find the date, we split the line on spaces and iterate on words
	# until we find a month. This cannot work with files whose owner is a
	# user named "Jan", or "Feb", etc. However, it's unlikely that '/'
	# will be owned by a user whose name is a month. So we first look at
	# the extended ls output of the root directory to decide how many
	# words should be skipped to get the date.

	# On HPUX /bin/sh, "set" interprets "-rw-r--r--" as options, so the "x" below.
	set x`$ls_command /`

	# Find which argument is the month.
	month=
	command=
	until test $month
	do
	test $# -gt 0 \|\| error "failed parsing '$ls_command /' output"
	shift
	# Add another shift to the command.
	command="$command shift;"
	mon_to_month $1
	done

	test -n "$month" \|\| error "failed parsing '$ls_command /' output"

	# Get the extended ls output of the file or directory.
	set dummy x`eval "$ls_command \"\\\$save_arg1\""`

	# Remove all preceding arguments
	eval $command

	# Because of the dummy argument above, month is in $2.
	#
	# On a POSIX system, we should have
	# $# = 5
	# $1 = file size
	# $2 = month
	# $3 = day
	# $4 = year or time
	# $5 = filename
	#
	# On Darwin 7.7.0 and 7.6.0, we have
	# $# = 4
	# $1 = day
	# $2 = month
	# $3 = year or time
	# $4 = filename

	# Get the month.
	mon_to_month $2

	case $3 in
	???*) day=$1;;
	*) day=$3; shift;;
	esac

	# Here we have to deal with the problem that the ls output gives either
	# the time of day or the year.
	case $3 in
	:) set `date`; eval year=\$$#
	case $2 in
	Jan) nummonthtod=1;;
	Feb) nummonthtod=2;;
	Mar) nummonthtod=3;;
	Apr) nummonthtod=4;;
	May) nummonthtod=5;;
	Jun) nummonthtod=6;;
	Jul) nummonthtod=7;;
	Aug) nummonthtod=8;;
	Sep) nummonthtod=9;;
	Oct) nummonthtod=10;;
	Nov) nummonthtod=11;;
	Dec) nummonthtod=12;;
	esac
	# For the first six months of the year the time notation can also
	# be used for files modified in the last year.
	if (expr $nummonth \> $nummonthtod) >/dev/null;
	then
	year=`expr $year - 1`
	fi;;
	*) year=$3;;
	esac

	# The result.
	echo $day $month $year

	# Local Variables:
	# mode: shell-script
	# sh-indentation: 2
	# eval: (add-hook 'before-save-hook 'time-stamp nil t)
	# time-stamp-start: "scriptversion="
	# time-stamp-format: "%Y-%02m-%02d.%02H"
	# time-stamp-time-zone: "UTC0"
	# time-stamp-end: "; # UTC"
	# End: