1. What is UNIX? What does UNIX stand for?
UNIX is a powerful, multiuser, multitasking operating system designed for flexibility and security. Originally developed in the 1970s, it's widely used on servers and workstations.
UNIX stands for: Uniplexed Information and Computing Service.
2. How to rename a file in UNIX?
mv old-file-name new-file-name
3. How to delete a directory in UNIX?
Empty directory:
rmdir directoryname
Directory with files:
rm -r directoryname
4. What is the difference between UNIX and LINUX?
| Feature | UNIX | LINUX |
|---|---|---|
| Cost | Usually proprietary and paid | Mostly free and open source |
| Usage | Servers, mainframes, workstations | Servers, desktops, mobile devices |
| File Systems | jfs, gpfs, hfs, xfs, zfs | ext2/3/4, xfs, btrfs, FAT, NTFS |
| Source Code | Closed | Open source |
| Examples | AIX, Solaris, HP-UX | Ubuntu, CentOS, Fedora |
5. How to change a password in UNIX?
passwd
6. How to find a file in UNIX?
find . -name "filename"
7. How to use grep command in UNIX?
The grep command searches for patterns in files.
grep [options] pattern [file...]
Example:
grep "error" logfile.txt
8. How to kill a process in UNIX?
kill -SIGTERM PID # Graceful stop
kill -9 PID # Forceful kill
killall process_name # Kill by name
9. What is UNIX shell scripting?
Shell scripting involves writing a sequence of UNIX commands in a file to automate repetitive tasks.
10. How to run a shell script in UNIX?
cd /path/to/script
nano script.sh # or any editor
chmod +x script.sh # make it executable
./script.sh # run the script
11. How to write a function in UNIX shell script?
myFunction() {
echo "Hello World"
}
myFunction
12. How to add comments in UNIX shell script?
# This is a comment
13. What is the difference between Kill and Kill -9 in UNIX?
- kill: Sends SIGTERM (15) – graceful termination.
- kill -9: Sends SIGKILL – immediate and forceful termination.
14. Difference between CAT and VI commands in UNIX?
- cat: Displays or creates files.
- vi: Interactive full-screen text editor.
15. What are the different dialects in UNIX?
- AT&T UNIX (System V)
- BSD UNIX (Berkeley Software Distribution)
- Microsoft XENIX
- HP-UX (Hewlett-Packard)
- AIX (IBM)
- Solaris (Sun Microsystems)
16. Difference between MV and CP commands in UNIX?
- mv: Moves or renames a file (original removed).
- cp: Copies a file (original remains).
17. Different ways to create a file in UNIX?
cat > filename
touch filename
echo "Text" > filename
printf "Text\n" > filename
18. What is the use of awk command in UNIX?
The awk command is used for pattern scanning and text processing.
awk '{print $1}' filename
9. How to copy a directory in UNIX?
cp -R source_dir/ destination_dir/
20. What is the UNIX command to create a shortcut for tail?
alias mytail='tail -n 200'
21. How to change file permissions in UNIX?
chmod 755 filename
22. How to change the owner of a file in UNIX?
chown newowner filename
23. How to view file permissions in UNIX?
ls -l
24. How to list running processes in UNIX?
ps aux
25. What is the difference between a foreground and a background process?
Foreground: Runs in the current terminal.
Background: Runs independently of the terminal using &.
26. How to run a command in the background?
command &
27. What is the use of the find command?
find /path -name "filename"
28. What is the use of the sed command?
sed 's/old/new/g' filename
29. How to compress a file using gzip?
gzip filename
30. How to extract a .tar.gz file?
tar -xzvf file.tar.gz
31. How to check disk space usage?
df -h
32. How to check memory usage?
free -m
33. How to check current logged-in users?
who
34. What is the use of set -x and set +x in shell scripting?
They enable (set -x) and disable (set +x) debugging mode in shell scripts.
35. What are environment variables? How to list them?
printenv
36. What is the difference between .bashrc and .bash_profile?
- .bashrc: Executes on interactive non-login shell.
- .bash_profile: Executes on login shell.
37. How to schedule a job in UNIX?
crontab -e
38. What is shebang (#!) in UNIX shell scripts?
#!/bin/bash