I'd like to make validation about time stamp of one of my log file. But it seems I have problem on my expression in case statement.

TIME value might be something like 11:49 or 2011. And I just want to check whether it is HH:MM format or not. Code is in below.
It is always saying year format althought file is in HH:MM format

TIME=`ls -lrth  /var/log/*.log |  grep -i upg | tail -1 | awk '{print $8}'`
echo "$TIME"
if [[ $TIME != "" ]]
  case TIME in
     "[0-23]+ :[0-59]")
  *) echo "Year format";;

echo "$validation

Update : I tried "[0-2][0-9]:[0-5][0-9]") but validation still return fail.

  • mibzer. You put what you call a comment into an anser. You, as the questioner, should confine your comments to comment entries (not Answers). When you have new significant data which doesn't easily fit into a comment, just update your answer, and refer to that in you comment.... Re your problem: you are mixing 2 types of expressios: glob style expressions and regular expressions. The bash case statement uses regular expressions. You need to remove the "quotes" ... bash regular expressions need to be exposed; not protected by quotes... If you need spaces, just escape them with \ – Peter.O Jul 18 '12 at 13:02
  • @Peter.O Thank you Peter and sorry for confusion. – mibzer Jul 18 '12 at 14:00
  • There is a mistake in my previous comment: case uses a glob style expression. – Peter.O Jul 18 '12 at 15:07
  • 1
    I think you're on the right track using case expressions, but you don't understand the rules of the character class expressions, i.e. [0-23] means "only 1 char matching" either 1). the range 0-2 (i.e. 0,1,2) OR 2) the single number number 3, NOT 0 hrs to 23 hrs as I'm guessing you mean. ---- Inside sq-brackets, each char stands for itself as a match for one char, excepting when the range notation is use as 0-2. You can use reg expers in this case to get mostly what you want, ie case TIME in [0-2][0-9]\ :[0-5][0-9]). Read it one sq-brkt at a time, what ever inside is a single match. GL. – shellter Jul 19 '12 at 4:38

The problem is that you can't check TIME with [0-23]+ :[0-59] expression.

There are several ways to do it:

  • To split your variable and check each part separately:
TIME="06:25" ; 
[[ $TIME != "" ]] && \
[ ${TIME%:*} -le 23 -a ${TIME%:*} -ge 0 -a \
        ${TIME#*:} -le 59 -a ${TIME#*:} -ge 0 ] && echo ok
  • To check it with common regex, but it will accept some cases of wrong time (like 28:59):
  • please see my below comment. – mibzer Jul 18 '12 at 12:45
  • your first advice worked thx, but I have one more question what is TIME%:* and TIME#* mean ? . I haven't used them before – mibzer Jul 18 '12 at 12:56
  • 1
    TIME%:* delete all symbols after first : from the beginning of the variable, TIME#* delete all symbols after first : from the end of the variable. You can find more detailed explanation here: tldp.org/LDP/abs/html/parameter-substitution.html – rush Jul 18 '12 at 13:08
  • 1
    You can be exact with expression matching: 1. "normal" regular expression, using =~: [[ $time =~ ^([01][0-9]|2[0-4]):[0-5][0-9]$ ]] 2. glob expression, using ==: [[ $time == @([01][0-9]|2[0-4]):[0-5][0-9] ]] – Peter.O Jul 18 '12 at 15:14

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