Linux: How to view log files on the shell?

Many Linux servers are administered on the commandline e.g. with an SSH connection. In the following article, I will explain several shell commands that make it easy to view logfiles. These commands will work on all major Linux distributions inc. CentOS, Debian, Fedora and Ubuntu.

Get the last N lines of a log file

The most important command is "tail". Tail can be used to read the last lines from a file. Examples:

Get the last 100 lines from the Debian mail log file:

tail -n 100 /var/log/mail.log

Get new lines from a file continuously

To get all newly added lines from a log file in realtime on the shell, use the command:

tail -f /var/log/mail.log

to quit tail and go back to the command line press the keys [ctrl] + [c]

Get the result line by line

If you want to get the last 1000 lines from a log file and they do not fit into your shell window, you can use the command "more" to be able to view them line by line.

tail -n 1000 /var/log/mail.log | more

press [space] to go to the next line or [ctrl] + [c] to quit.

Search in a log file

If you want to search for a specific term in a large file, the command "grep" comes in handy. Example: We search for the email address "[email protected]" in the mail log file:

grep "[email protected]" /var/log/mail.log

To store the result of the above grep command into a file named result.txt, use this command:

grep "[email protected]" /var/log/mail.log > /tmp/result.txt

View the whole content of a file

If you want to view the whole content of a file on the shell, use the command "cat". Example:

cat /proc/cpuinfo

will show you detailed info about the CPU of your computer.

3 thoughts on “Linux: How to view log files on the shell?”

  1. Avatar

    You can also use the “less” command.

    less /var/log/mail.log

    [q] to quit.
    [/] “text” and [enter] to search a pattern.
    [G] to go to the end of the file.
    [gg] to go to begining of the file.

  2. Avatar

    can u give me the ans of ” find a way to locate log file in web site contents?”

    • Avatar

      this also “list all the network connections to publlic ip’s?”
      how to find it in kali linux


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