"Next Date" Script

Shell Programming and Scripting
1

Good afternoon to you all

I need your help

I need a shell script that reads a date and then returns the immediate next date.

For example:

I have a file dates.txt containing these dates:

"2010-03-21 22:30:00"
"2010-03-18 21:10:00"
"2010-03-03 14:42:00"
"2010-04-28 09:30:10"

What I want to do, is to define a date="2010-03-17 20:00:00" and parse throught the dates.txt and find de imediate next date (in this case it would be "2010-03-18 21:10:00").

Can you please help me

Thkx in advance

2

check the FAQ article:

http://www.unix.com/answers-frequently-asked-questions/13785-yesterdays-date-date-arithmetic.html

Think you should find some answers in there.

HTH

---------- Post updated at 03:27 PM ---------- Previous update was at 03:04 PM ----------

Having said that....I got interested :slight_smile:

the following (bash)code snippet should be close to what you're after:

d="2010-03-17 20:00:00" 
dn=$(echo $d | tr -d ":- ")
t=$dn
while read s
do
  dd=$(($(tr -d ":- \""<<<$s)-$dn))
  [[ $dd -gt 0 ]] && [[ $dd -lt $t ]] && t=$dd && ss=$s
done < infile
echo $ss
"2010-03-18 21:10:00"

HTH:D

3

Change to epoc and use it.

file

2010-03-21 22:30:00
2010-03-18 21:10:00
2010-03-03 14:42:00
2010-04-28 09:30:10

Using gnu date:

#!/bin/ksh93 or bash or ...
cat file | while read line
do
    day=$(date -u --date="$line" +"%s")
    ((day-=86400))
    yesterday=$( date -u --date="1970-01-01 $day seconds" '+%Y-%m-%d H:%M:%S'   )
    echo "$line => $yesterday"
done

Or ksh93 printf

#!/bin/ksh93
cat file | while read line
do
    day=$(printf "%(%#)T" "$line")
    ((day-=86400))
    yesterday=$( printf "%(%Y-%m-%d %H:%M:%S)T \n" "#$day"   )
    echo "$line => $yesterday"
done