Check if given strftime format matches a date

问题

I have strftime format of time, let's say (%Y-%m-%d %H:%M:%S) and a file which should contain this kind of data e.g. (2012-02-11 17:15:00). I need to check if given pattern actually matches the data. How to approach this? awk, date?

EDIT: More info: The user enters the strftime format, let's say on input. Then he enters a file which should contain those dates. I need to make sure, that those data are valid (he didn't make a mistake). So I need to check the rows in the input file and see, if there are data that matches the given pattern. Example:

user enters strftime format: (%Y-%m-%d %H:%M:%S)

input file: (2012-02-11 17:15:00) long sentence

VALID
user enters strftime format: Date[%Y.%m.%d %H:%M:%S]

input file: Date-2012.02.11 17:15:00- long sentence

INVALID

回答1:

If you allow an external helper binary, I've written dateutils to batch process date and time data.

dconv -q -i '(%Y-%m-%d %H:%M:%S)' <<EOF
not a match: 2012-04-10 12:00:00
a match: (2012-04-10 13:00:00)
EOF

will give

2012-04-10T13:00:00

-i is the input format, -q suppresses warnings. And dconv tries to convert input lines to output lines (in this case it converts matching lines to ISO standard format.

So using this, a file matches completely if the number of input lines equals the number of output lines.

回答2:

If you want to check current datetime:

echo "(2012-02-11 17:15:00)" | grep "$(date "+%Y-%m-%d %H:%M:%S")"

If some other you need GNU date (-d option). This works for me:

echo "(2012-02-11 17:15:00)" | 
grep "$(date -d "2012-02-11 17:15:00"  "+%Y-%m-%d %H:%M:%S")"

回答3:

I would take a brute force approach to this: replace any %X specifier with a corresponding regular expression, then you can filter out lines that don't match the resulting generated regex:

user_format="%Y-%m-%d"
awk -v fmt_string="$user_format" '
  BEGIN {
    gsub(/[][(){}?|*+.]/ "\\&", fmt_string)  # protect any regex-special chars
    gsub(/%Y/, "([0-9]{4})", fmt_string)
    gsub(/%m/, "(0[1-9]|1[012])", fmt_string)
    gsub(/%d/, "(0[1-9]|[12][0-9]|3[01])", fmt_string)
    # and so on
  }
  $0 !~ "^" fmt_string {print "line " NR " does not match: " $0}
' filename

来源：https://stackoverflow.com/questions/10085538/check-if-given-strftime-format-matches-a-date

标签

bash

date

awk

gawk

strftime