How do I view the last 100 lines of a log file?
Using tail for recent lines
The tail command prints the end of a file, which is where the newest entries usually appear. The -n flag sets how many lines to show, and the file path comes last. For a quick check after a deploy, this is often the fastest command you can run.
- tail -n 100 /path/to/file.log for the last hundred lines
- tail -f /path/to/file.log to follow new entries live
- Combine with grep to filter for errors
Reading longer logs
For a large file, less lets you scroll and search without loading everything into your terminal at once. Press capital G to jump to the end and slash followed by a word to search. Piping output through grep narrows the view to just the lines that matter.
Permissions and paths
Some log files belong to root or a service account, so you may need sudo to read them. Confirm the exact path first, since many services write logs to a directory rather than a single file. If the file is empty, check whether the service logs to the system journal instead.
Common mistakes
- Forgetting sudo and reading a permissions error as an empty file.
- Running tail -f on a huge file without limiting the output first.
- Looking in the wrong directory when the service writes to the journal.
