Reading a file after nth line

Shell Programming and Scripting
1

I know how to read a file line by line. But don't to how to skip to a line matching a criteria and then continue reading it till the end.

This is a log file. The input is a timestamp.

  1. Find the timestamp in the log file
  2. Read the remaining lines one at a time till EOF.

How can I do this?

2 
sed -ne '/timestamp/,$p' yourfile
1 Like
3

you mean, p will have the rest of the file and i read it line by line?

4

No. It's a sed script, telling it not to print the contents of the file, until the timestamp is found. From there on to the rest, print the file as it is.

5

Ok here is my code

while read line
        do
                        processLine
        done < $logFile

Now where and how does your statement fit here?

---------- Post updated at 05:49 PM ---------- Previous update was at 05:34 PM ----------

I haven't worked much in unix, so finding it hard to perform simple operations

6

If you want to do some "processing" on lines read after "timestamp" occured,

 
sed -ne '/'"${timestamp}"'/,$p' yourfile | while read line 
do
## do processing
done
1 Like
7

I am trying use a variable for timestamp like

sed -ne '/$timestamp/,$p' yourfile | while read line

And sed is not matching any records. I tried '$timestamp', "$timestamp"....nothing seems to be working.

---------- Post updated at 06:53 PM ---------- Previous update was at 06:48 PM ----------

I tried

sed -ne '/2011\/06\/28 11\:16\:14/,$p' test.log

on command prompt and it works fine.

8 
 
check my last edited post and see if it works.
9

nope, it doesn't work. I am really not understanding the usage of single and double quotes.
Can you please provide some pointers to read up?

10

If my timestamp="11:16:14" then

sed -ne '/'"$timestamp"'/,$p' $logFile

works fine

And if timestamp="2011/06/28 11:16:14" then nothing works.
Any reasons?

---------- Post updated at 12:35 PM ---------- Previous update was at 09:04 AM ----------

work around
I replaced "/" with "\/" and ":" with "\:" and the above command worked like charm.