2021-10-11 18:37:13 -03:00

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#!/bin/sh
#@(#)day.sh 1.1 94/10/31 SMI
#
#
# prints todays or yesterdays date in the format mm_dd_yy
#
USAGE="usage: $0 <today | yesterday>"
yesterday () {
date | awk '
BEGIN{
m["Jan"] = 1; m["Feb"] = 2; m["Mar"] = 3; m["Apr"] = 4
m["May"] = 5; m["Jun"] = 6; m["Jul"] = 7; m["Aug"] = 8
m["Sep"] = 9; m["Oct"] = 10; m["Nov"] = 11; m["Dec"] = 12
d[1] = 31; d[2] = 28; d[3] = 31; d[4] = 30; d[5] = 31; d[6] = 30
d[7] = 31; d[8] = 31; d[9] = 30; d[10] = 31; d[11] = 30; d[12] = 31
}
{
yr = $6; mon = m[$2]; day = $3
if (yr % 4 == 0 && (yr % 100 != 0 || yr % 400 == 0))
d[2] += 1
day -= 1
if (day == 0)
{
mon -= 1;
if (mon == 0)
{
mon = 12
yr -= 1
}
day = d[mon]
}
printf("%d%d_%d%d_%d\n",mon / 10, mon % 10, \
day / 10, day % 10, yr % 100);
}'
}
# Program:
[ -z "$1" ] && {
echo $USAGE
exit 1
}
case "$1" in
today)
date '+%m_%d_%y';exit 0;;
yesterday)
yesterday;exit 0;;
*)
echo $USAGE;exit 1;;
esac