Bash Validate Date

Validate date format in a shell script

Use date

date "+%d/%m/%Y" -d "09/99/2013" > /dev/null  2>&1
 is_valid=$?

The date string must be in "MM/DD/YYYY" format.

If you do not get 0 then date is in invalid format.

check if argument is a valid date in bash shell

You can check with date -d "datestring"

So date -d "12/31/2012" is valid, but using hyphens, e.g. date -d "12-31-2012", is not valid for date.

You can also use words: date -d 'yesterday' or date -d '1 week ago' are both valid.

Bash validate date

The BSD date that ships with Mac OS X doesn't support the -d option (or rather, it uses -d for something entirely different). Either install GNU date, or use the following to validate your input string:

date -f "%Y-%m-%d" -j "2012-02-29" >/dev/null 2>&1

The -f provides the input format, and the -j tells date to simply output the date, not attempt to set the system clock.

Validate a date in shell script (with the BSD date)

FreeBSD date does not support the -d flag,

date -f "%Y-%m-%d" -j "2017-01-28" >/dev/null 2>&1
is_valid=$?

(or)

date -f "%Y-%m-%d" -j "2017-01-28" >/dev/null 2>&1 && printf "Date validation success\n" || printf "Date validation fail\n"

DATE validation using regex in awk

In GNU awk the \d and \z sequences are not valid regex operators (a quick web search doesn't show these as valid regex operators in a couple others flavors of awk though by no means an exhaustive search).

I'd suggest replacing the \d with [0-9] or [[:digit:]]; as for the \z you could try \> or \y.

One other issue is the use of . as a wildcard match in the time component; if you know all times will use a colon (:) as a delimiter then I'd use an explicit colon.

Rolling these changes into the current code (and fixing a couple cut-n-paste/syntax issues):

awk -F '|' 'BEGIN {OFS=FS}
{ if ($1 ~ /^[0-9]{1,2}\/[0-9]{1,2}\/[0-9]{4} [0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2} [AP]M\y/)
print
}'

This generates:

04/21/2014 02:04:55 AM|34536
12/31/2021 03:29:15 AM|87612

NOTES:

• obviously (?) this code assumes a specific date/time format and thus ...
• this code will not match on other valid date/time formats (eg, won't match on 2021/12/31)
• the use of [0-9] opens you up to matching on strings that are not valid dates and/or times, eg, this code will match on 99/99/2022 and 99:99:99); OP can address some of these by limiting the series of digits that can be matched in a given position (eg, [0-2][0-9] for hours) but even this is problematic since 29 will match but is not a valid hour
• as alluded to in comments ... validating dates/times is doable but will require a good bit more code (alternatively run a web search on bash awk validate dates times for additional ideas)

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