Dealing with date and time is more or less a common task when batch scripting. Awk provides simple date and time function for basic time/date manipulation needs.
1) systime()
2) strftime()
3) mktime()

1) systime().
This is the the number of seconds since the system epoch. systime is commonly used to create a random number seed.

Code: [Select]C:\>awk "BEGIN{ print systime(); } "
1389169226

2) strftime().
This is a function to format a timestamp based on the contents of the format string. This is useful if you want to create a time stamp on windows.eg To get the full 4-digits year, use the "%Y" format
Code: [Select]C:\>awk "BEGIN{ print strftime(\"%Y\") } "
2014


To get YYYY-MM-DD-HH-mm-ss timestamp
Code: [Select]C:\>awk "BEGIN{ print strftime(\"%Y-%m-%d-%H-%M-%S\") } "
2014-01-08-16-24-23

you can then capture the results in the usual DOS for loop.


3) mktime( date specs )
"date specs" argument to mktime is a string of the form YYYY MM DD HH MM SS.
YYYY = full year
MM = month, 1 to 12
DD = day, 1 to 31
HH = hour, 0 to 23
mm = minute, 0 to 59
SS = seconds, 0 to 59
mktime will create a timestamp similar to systime()
eg
Code: [Select]C:\>awk "BEGIN{string=\"2014 01 01 0 0 0\"; print mktime(string) } "
1388505600

mktime is commonly use to get time difference. eg compare the date "2014 01 01 0 0 0 " against today's date and get their difference (in secs)

Code: [Select]C:\>awk "BEGIN{string=\"2014 01 01 0 0 0\"; s=mktime(string); print (systime() - s) } "
664866
this is useful if for example, you are PARSING a log file and filtering the date/time column for a specific date.


to be continued

- brianadamsSometimes you many want to merge a collection of similar items. eg
Code: [Select]C_1,KOG0155
C_1,KOG0306
C_2,KOG3259
C_3,KOG0931
C_2,KOG3638
C_4,KOG0956
C_6,KOG0155
C_1,KOG0306
C_3,KOG3259
C_4,KOG0931
C_5,KOG3638
C_1,KOG0956

to become something like this:
Code: [Select]C_1,KOG0155 ,KOG0306,KOG0306,KOG0956
C_2,KOG3259, KOG3638
C_3,KOG0931, KOG3259
C_4,KOG0956, KOG0931
C_6,KOG0155
C_5,KOG3638

You can make use of associative arrays in awk

Code: [Select]C:\>awk -F"," "{ array[$1] = array[$1]\",\"$2 }END{ for(idx in array) print idx, a[idx]}"
C_3 ,KOG0931,KOG3259
C_4 ,KOG0956,KOG0931
C_5 ,KOG3638
C_6 ,KOG0155
C_1 ,KOG0155,KOG0306,KOG0306,KOG0956
C_2 ,KOG3259,KOG3638
Lots of awk stuff lately from you.
Quote from: briandams on January 16, 2014, 06:22:54 AM

That's how you can call an external DOS command and have it displayed inside awk program itself.

getline returns 1 if it finds a record, and 0 if the end of the file is encountered. If there is some error in getting a record, such as a file that cannot be opened, then getline returns -1. It is generally good practice to always explicitly test for >0 while reading a file or handling input from pipes.

to be continued

- brianadams

The error is stored within AWK's error variable. It does not pass the error back to the calling batch file or CMD window you have open.

awk internally doesn't have a mechanism for checking file existence such as -f test for linux. so most of the time if you want to do that then have to make a system call , OR to call getline and check -1.

Quote

The error is stored within AWK's error variable. It does not pass the error back to the calling batch file or CMD window you have open.

awk internally doesn't have a mechanism for checking file existence such as -f test for linux. so most of the time if you want to do that then have to make a system call , OR to call getline and check -1.

copy-pasting your posts from another forum

Then why not use the shells built-in functionality to check for the file existence before running your AWK command.

Code: [Select]IF EXIST foo.txt awk.........

But when responses like the above are copy-pasted verbatim to rather different questions, that's just a bit weird, I think.

I wondered about that.