Is there a constant variable in awk, that store today's date? If not, is there a way that can store today's date for daily use?
Let's say we have below file:
boo,foo,2016-08-30
foo,boo,2016-07-31
And I need to compare the date $3 in the file, with today's date, regardless what it is.
i.e below script
awk -F, '{if($3>"2015-08-23"){print $0}}'
where 2015-08-23 will be changed by the current date.
There are no built-in functions in standard awk to get a date, but
the date can easily be assigned to a variable.
awk -F, -v date="$(date +%Y-%m-%d)" '$3>date'
or in an awk script
BEGIN {
str = "date +%Y-%m-%d";
str | getline date;
close(str);
}
$3>date
gawk, does have built-in time functions, and strftime can be used.
gawk -F, 'BEGIN{date=strftime("%Y-%m-%d")}$3>date'
date's format does not have spaces.
15-08-24 while for right comparison it should be 2015-08-24 is there a way to change it to this format?
Y is, in fact, in the lower-case. As for changing the format, you can check your system's man date, or the standard linked above.
awk pattern of just $3>date (with empty=default action) no /.../ slashes
using the getline workaround:
awk -F, ' BEGIN { "date +%Y-%m-%d" | getline a } { if ( $3>a ) { print 0 }} ' file
If you like to get the current time_t, this can be done by calling srand() and then call t = srand().
$ awk 'BEGIN{srand(); print srand()}'
1440536144
This works as posix requires the random function to be initialized with the current time if called without arg and to return the previous seed.
awk implementations and used to be the most portable way to get the current Unix epoch time at all (let alone in awk). But not all. All POSIX requires is that the seed be based on the time of the day (a pretty useless requirement IMO), not specifically the unix epoch time, which allows implementations to use something less predictable and that changes more often than every second. Now I can't remember which awk implementation that doesn't work on.
You can do it by assigning a variable:
cat /path/to/file | awk -v date="$(date +'%Y-%m-%d')" -F, '{if($3>date){print $0}}'
