Shell Programming and Scripting

You can't have a space between the variable= and the value to be assigned to that variable. The syntax you used, sets st to an empty string and includes it in the environment of the command that follows. But that won't get rid of the Thu Jan 29 or the CST 2015

Note that your original post didn't say anything about the string started at appearing in the input (and was not in your sample input).

Assuming you're working in an English locale, you could try something like:

Code:

awk '
match($0, /[[:digit:]]{1,2}:[[:digit:]]{2}:[[:digit:]]{2} *([AP]M){0,1}/) {
	print substr($0, RSTART, RLENGTH)
}' file

The ERE can be simplified if you only have 24-hour format times.

With the following contents in your input file:

Code:

Nothing found on this line
 a.sh start time is Fri Jan  9 17:17:33 CST 2015
a.sh end time is Fri Jan  9 17:47:33 CST 2015
Single digit hour Fri Jan  9  5:50:59 PM CST 2015
Double digit hour Sat Jan 10 11:22:33 AM CST 2015
No space single Fri Jan  9  5:50:59PM CST 2015
No space double Sat Jan 10 11:22:33AM CST 2015

it produces the output:

Code:

17:17:33 
17:47:33 
5:50:59 PM
11:22:33 AM
5:50:59PM
11:22:33AM

Fairly simple changes would allow you to find more than one timestamp on a line.

If you want to try this on a Solaris/SunOS system, change awk to /usr/xpg4/bin/awk, /usr/xpg6/bin/awk, or nawk

Hello Don,

Thank you for nice code, I think we need to add --re-interval in that as follows as we are using ERE here.

Code:

awk --re-interval '
match($0, /[[:digit:]]{1,2}:[[:digit:]]{2}:[[:digit:]]{2} *([AP]M){0,1}/) {
print substr($0, RSTART, RLENGTH)
}'  Input_file

Output will be as follows.

Code:

17:17:33
17:47:33

Thanks,
R. Singh

Hi Ravinder,
--re-interval (or --posix) is needed on gawk to get POSIX conforming EREs, but it is not needed for any version of awk that conforms to the POSIX standards.

The output that I showed in post #8 was the exact output produced by the awk command I showed in that thread when it was run on OS X Yosemite.

Could be quite easier

Solution 1:

Code:

	awk '{print $8}' afile.txt

Option 2:

Code:

	while read vScript vStatus sTime sIs sDay sMonth sNum sTime sReg sYear
	do 	echo "$sTime"
	done<afile.txt

What you asked in first post, and what you described your post #7 does not match.
You're looking for the string "started at" but your example post #1, shows us there is only "start at".

If you care about the status, feel free to add a check for "vStatus", wether its "start" or "end".

hth

This will probably work for about half of a year's input assuming that all lines are in exactly the same format and that the CST is referring to US Central Standard timezone. It won't work when dayligth savings time is in effect. And, of course, it will only work for dates in 2015.

The following modifications should work year around for the sample input provided in 2015:

Code:

string1='a.sh start time is Fri Jan  9 17:17:33 CST 2015';
string1=${string1%* C?T 2015}
string1=${string1##* }

string2='a.sh start time is Fri Jun 12 17:17:33 CDT 2015';
string2=${string2%* C[DS]T 2015}
string2=${string2##* }

clear && echo $string1 && echo "" && echo $string2

The ? will match any character; the [DS] will match an uppercase D or an uppercase S. I will leave the modifications needed to recognize additional years as an exercise for the reader. If some of the dates being processed come from other timezones, I would suggest using a different approach.

You seem to be mixing the awk match() and split() functions. But, I get a syntax error when I try this code. The match() function takes two arguments (string to be matched and an ERE to match) and sets various awk variables to indicate whether or not a match was found and, if there was a match, the starting position of the match and the length of the match. The awk script I suggested in post #8 in this thread uses match() this way.

The awk split() function creates an array of values corresponding to values separated by field separators specify by an ERE. With the ERE you use, the desired date would not appear in the array at all since the ERE selects the date as the field separator.

Hi All, Thanks for replying. I tried Bigsanch's code modified by Don(#12). It worked fine for me. However need to do a thorough testing before implementing.

Also my original code wrked after removing the extra space after =(#8). But I am getting Thu Jan 29 15:01:17 CST 2015 in a variable. So I was looking if anyways I can extract only the time from the above.

The "from the above" is a little ambiguous. There are suggestions above in this thread from several volunteers trying to help you, most of which try to just extract a timestamp from your sample data.

What operating system and shell are you using? As has been pointed out, some of the suggestions above will work on some systems but not on others.

Instead of just giving us two strings to parse, describe the strings you want to parse: