Essential Unix/Linux Command-Line Tips for Increased Productivity

Learn how to safely delete a massive 200 GB log file without overloading I/O by truncating it with : > /path/to/file.log and then removing it with rm /path/to/file.log.

Record terminal output using the script utility, e.g., script my.terminal.session, and later view the log with more, less, or cat.

Restore an accidentally removed /tmp directory by recreating it and resetting permissions: mkdir /tmp, chmod 1777 /tmp, chown root:root /tmp, then verify with ls -ld /tmp.

Lock a folder such as /downloads by setting permissions to chmod 0000 /downloads; root can still access it, and you can unlock it later with chmod 0755 /downloads.

Protect a file in Vim with a password using vim +X filename or the :X command before exiting, which prompts for a passphrase.

Clear a garbled terminal screen instantly with reset.

Display command output in human‑readable form by adding -h or -H to GNU/BSD tools, e.g., ls -lh, df -h, free -m, du -h, stat -c %A /boot, sort -h -a file, lscpu, and tree -h.

Show known user information on Linux with lslogins (or logins on BSD) and review the formatted output.

Remove files unintentionally extracted by a tarball in /var/www/html with cd /var/www/html/ followed by /bin/rm -f "$(tar ztf /path/to/file.tar.gz)".

Replace top with the more user‑friendly htop by running sudo htop.

Rerun the most recent command using !!, repeat a command that starts with a specific prefix using !foo, or reuse the last argument with !$ (e.g., sudo vi !$().

Set a reminder to leave the terminal at a specific time with leave +hhmm, where hhmm denotes the hour and minute.

Quickly return to the previous directory with cd -, go to the home directory with cd, and define a search path for cd using export CDPATH=/var/www:/nas10.

Edit a file while viewing it with less by pressing v, which launches the editor defined by $EDITOR.

List all directories or files on the system using find / -type d | less and find / -type f | less, or limit the search to $HOME with appropriate options.

Create an entire directory tree in one command with mkdir -p /jail/{dev,bin,sbin,etc,usr,lib,lib64} and verify with ls -l /jail/.

Copy a single file to multiple destinations efficiently using

echo /usr/dir1 /var/dir2 /nas/dir3 | xargs -n 1 cp -v /path/to/file

.

Compare two directories quickly with diff /tmp/r/ /tmp/s/ after listing their contents.

Reformat text files for better readability with fmt file.txt (or fmt -s file.txt to split long lines without re‑flowing).

Use tee to display command output on the screen while simultaneously writing it to a log file, e.g., mycoolapp arg1 arg2 input.file | tee my.log.