Shell Programming and Scripting

Hi

I am newbie.My requirement is:
I have start time :Wed Apr 30 3:30:45
End time :Wed Apr 30 3:35:45
which is stored in a file.
I have to extract timestamp 3:30:45 using awk. And Subtract the same

The script:
----------
#!/bin/ksh
LOG_FILE=$1

START_TIME=`head -2 $LOG_FILE `
echo $START_TIME
NUM_FIELDS=`echo $START_TIME| awk '{print NF}'`

count=0
Time_Stamp=`echo $START_TIME| awk -F ':' '{print $NUM_FIELDS}'`
echo 'Time'
echo $Time_Stamp
while [$count -lt $NUM_FIELDS]
do
count=`expr $count + 1`
Time_Stamp=`echo $START_TIME| awk '{print $NUM_FIELDS}'`
echo $Time_Stamp
done
The script is not working.
Please let me know how to proceed.

What does the input file look like? Are you trying to read the file and find the End time, or is the End time on the second line?

You're probably better off doing the whole thing in awk than trying to loop over the file in the shell and calling awk on minimal snippets of extracted information.

See also the FAQ secion, e.g. https://www.unix.com/tips-tutorials/3...tion-bash.html and https://www.unix.com/answers-frequent...rithmetic.html