[NTLUG:Discuss] verify that a text string is a valid date.

[Fred James]

Chris Cox wrote:

>
>$ mydate="2006-02-01"
>$ date -d "$mydate"
>Feb 28 00:00:00 CST 2006
>$ echo $?
>0
>$ mybaddate="2006-02-29"
>$ date -d "$mybaddate"
>date: invalid date `2006-02-29'
>$ echo $?
>1
>  
>
Chris Cox
My Mileage Did Vary - see below - as I was unable to duplicate the 
results on any of the 5 different types of machines/OSs I have available 
to me.  Did I do it wrong?
Regards
Fred James

Bash on Mandrake 9.2
"
$ mydate="2006-02-01"
$ date -d "$mydate"
Wed Feb  1 00:00:00 CST 2006
$ echo $?
0
$ mydate="2006-02-29"
$ date -d "$mydate"
Wed Mar  1 00:00:00 CST 2006
$ echo $?
0
"

Bourne on SGI IRIX 6.4, and 6.5.11m, Bourne on HP HP-UX B.11.11
[ran this script]
echo "mydate=\"2006-02-01\""
mydate="2006-02-01"
date -d "$mydate"
echo $?
echo "mydate=\"2006-02-29\""
mydate="2006-02-29"
date -d "$mydate"
echo $?
exit
[got this back]
"mydate="2006-02-01"
Bad conversion
Usage:
        date [-u] [+format]
        date [-u | -n] [[mmdd] HHMM | mmddHHMM[[cc]yy]][.ss]
        date [-a [-]sss.fff]
1
mydate="2006-02-29"
Bad conversion
Usage:
        date [-u] [+format]
        date [-u | -n] [[mmdd] HHMM | mmddHHMM[[cc]yy]][.ss]
        date [-a [-]sss.fff]
1
"

Bourne on Unisys Unix SVR4 2
[ran this script]
echo "mydate=\"2006-02-01\""
mydate="2006-02-01"
date -d "$mydate"
echo $?
echo "mydate=\"2006-02-29\""
mydate="2006-02-29"
date -d "$mydate"
echo $?
exit
[got this back]
"
mydate="2006-02-01"
date: bad conversion
1
mydate="2006-02-29"
date: bad conversion
1
"