How do you find the last occurrence of a string in a file?

How do you find the last occurrence of a string in a file?

6 Answers

1. Print last occurence of x (regex): grep x file | tail -1.
2. Alternatively: tac file | grep -m1 x.
3. Print file from first matching line to end: awk ‘/x/{flag = 1}; flag’ file.
4. Print file from last matching line to end (prints all lines in case of no match): tac file | awk ‘! flag; /x/{flag = 1};’ | tac.

How do I find the first 100 lines in Linux?

Type the following head command to display first 10 lines of a file named “bar.txt”:

1. head -10 bar.txt.
2. head -20 bar.txt.
3. sed -n 1,10p /etc/group.
4. sed -n 1,20p /etc/group.
5. awk ‘FNR <= 10’ /etc/passwd.
6. awk ‘FNR <= 20’ /etc/passwd.
7. perl -ne’1..10 and print’ /etc/passwd.
8. perl -ne’1..20 and print’ /etc/passwd.

How do you find the last occurrence of a character in a string in Linux?

If you like to find the exact index of the last occurrence of the character in the string, then you use the length function in the awk command.

How to extract log lines from a log file?

In order to do this, you need to open the log file and check the format of the date. For example, in my case, this is a sample log line from the log file we will using for demonstration. Now that we know the format of the date, proceed to extract the log lines.

When to delete the last line in a log file?

If there are more than one line of the last date specified in the range, then you need to include the next date after the specified last date in the range and delete the last line. For example, to print lines from April 7th to April 8th;

How to extract dates from a log file?

Apr 8 09:22:54 amos ntpd [1805]: Soliciting pool server 192.168.34. As you can see above, the date command prints the date and removes the leading zero so that the format of the date matches the dates on the log file.