20 Essential Unix/Linux Command-Line Tricks to Boost Your Productivity

1. Delete a large file

If a massive log file (e.g., 200 GB) makes rm or ls unresponsive, truncate it before removal:

> /path/to/file.log
# Or use the shell redirection syntax
: > /path/to/file.log
rm /path/to/file.log

2. Record terminal output

Use the script utility to capture everything displayed in the terminal. script my.terminal.session Run any commands (e.g., ls, date, sudo service foo stop) and then exit the session with exit, logout, or Ctrl‑D. The recorded file can be viewed with more, less, or cat.

3. Restore a deleted /tmp directory

Recreate the standard temporary directory with correct permissions and ownership:

mkdir /tmp
chmod 1777 /tmp
chown root:root /tmp
ls -ld /tmp

4. Lock a folder

To deny access to /downloads for non‑root users, set restrictive permissions: chmod 0000 /downloads Root can still access it; to restore normal access:

chmod 0755 /downloads

5. Password‑protect a file in Vim

Open a file with encryption using Vim’s +X flag: vim +X filename Alternatively, after editing, execute :X inside Vim to set a password.

6. Clear garbled screen output

Reset the terminal display:

reset

7. Human‑readable format for common commands

Append -h or -H to GNU/BSD utilities to get sizes in K, M, G, etc.

ls -lh
# human‑readable sizes
df -h
df -k
free -b
free -k
free -m
free -g
du -h
stat -c %A /boot
sort -h -a file
lscpu
lscpu -e
lscpu -e=cpu,node
tree -h
tree -h /boot

8. Show known user information

On Linux, use lslogins; on BSD, use logins:

lslogins
logins

Sample output lists UID, username, password lock status, last login, etc.

9. Remove files accidentally extracted in the wrong directory

If a tarball was extracted under /var/www/html instead of the intended project directory, delete the extracted files without touching other content:

cd /var/www/html/
/bin/rm -f "$(tar ztf /path/to/file.tar.gz)"

10. Replace top with htop

For a more user‑friendly process viewer, run:

sudo htop

11. Re‑run the previous command

Use !! to execute the last command, optionally with sudo:

!!
sudo !!

Run the most recent command starting with a specific prefix:

!foo
sudo !service

Use !$ to repeat the last argument of the previous command:

sudo vi !$

12. Set a timed reminder to leave the terminal

Schedule a reminder with the leave command (time format hhmm, 12‑hour clock assumed):

leave +hhmm

13. Quick directory navigation shortcuts

Return to the previous directory: cd - Go directly to the home directory: cd Define a search path for cd with CDPATH: export CDPATH=/var/www:/nas10 Now cd html jumps to /var/www/html without typing the full path.

14. Edit a file while viewing it with less

Press v inside less to open the file in the editor specified by $EDITOR. After editing, return to less to continue browsing.

15. List all directories or files on the system

List every directory and pipe through less:

find / -type d | less
find $HOME -type d -ls | less

List every regular file similarly:

find / -type f | less
find $HOME -type f -ls | less

16. Create a directory tree in one command

Use mkdir -p with brace expansion:

mkdir -p /jail/{dev,bin,sbin,etc,usr,lib,lib64}
ls -l /jail/

17. Copy a file to multiple directories at once

Instead of issuing several cp commands, feed the target directories to xargs:

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

18. Quickly find differences between two directories

Use diff on directory paths:

diff /tmp/r/ /tmp/s/

19. Reformat text with fmt

Wrap paragraphs to a uniform width: fmt file.txt To split long lines without re‑flowing short ones:

fmt -s file.txt

20. View output while writing it to a file

Pipe a command through tee to display on the screen and simultaneously log to a file:

mycoolapp arg1 arg2 input.file | tee my.log

tee

ensures the program’s output is both visible and saved.