os.Linux

# usage: touch_date <unix ts> <file>
touch_date()
{
	touch -d @$1 "$2"
}

# usage: last_modified <file>
last_modified()
{
	stat -c "%Y" "$1"
}

# usage: format_last_modified <file>
format_last_modified()
{
	# must strip nano-second part otherwise git gets very
	# confused, and makes up strange timestamps from the past
	# (chances are it decides to interpret it as a unix
	# timestamp).
	stat -c "%y" "$1" | sed -e '
s/^\([0-9]\{4\}\)-\([0-9]\{2\}\)-\([0-9]\{2\}\) \([0-9]\{2\}\):\([0-9]\{2\}\):\([0-9]\{2\}\)\.[0-9]* \(.*\)$/\1-\2-\3 \4:\5:\6 \7/'
}

# usage: head_n [count]
head_n()
{
	head -n "$1"
}

# usage: sha1 [file]
sha1()
{
	if [ $# = 1 ]
	then
		sha1sum "$1"
	else
		sha1sum
	fi
}

# usage: cp_a <src> <dst>
cp_a()
{
	cp -a "$1" "$2"
}

# usage: _tac
_tac()
{
	tac
}

_seq()
{
	seq "$@"
	return $?
}

_stat_size()
{
        stat -c %s "$1"
}