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Question-1. What is shell scripting?
Answer-1: Shell scripting is writing a series of commands in a file to automate tasks in Unix/Linux.
Question-2. What is Bash?
Answer-2: Bash (Bourne Again Shell) is a command-line interpreter and a scripting language for Unix/Linux.
Question-3. How do you create a shell script?
Answer-3: Create a file with .sh extension and add commands. Make it executable using chmod +x filename.
Question-4. How do you run a shell script?
Answer-4: Use ./scriptname.sh or bash scriptname.sh.
Question-5. What is the shebang (#!) in shell scripting?
Answer-5: It specifies the interpreter for the script. Example: #!/bin/bash.
Question-6. How do you define a variable in Bash?
Answer-6: Use variable_name=value. No spaces around the = sign.
Question-7. How do you access the value of a variable?
Answer-7: Use $variable_name.
Question-8. What are positional parameters in Bash?
Answer-8: They are special variables like $1, $2, representing script arguments passed during execution.
Question-9. How do you read input from the user in Bash?
Answer-9: Use the read command. Example: read username.
Question-10. What is the use of echo in shell scripting?
Answer-10: echo prints text or variables to the terminal.
Question-11. What is the purpose of test in shell scripting?
Answer-11: test evaluates conditional expressions and returns a status.
Question-12. What is the difference between = and == in Bash?
Answer-12: = is used for assigning values, while == is used for string comparison.
Question-13. How do you write an if statement in Bash?
Answer-13: Example: if [ condition ]; then commands; fi.
Question-14. How do you write a for loop in Bash?
Answer-14: Example: for var in list; do commands; done.
Question-15. What is the while loop syntax in Bash?
Answer-15: Example: while [ condition ]; do commands; done.
Question-16. How do you comment in a Bash script?
Answer-16: Use # for single-line comments.
Question-17. What are special variables $?, $0, and $$?
Answer-17: $?: Exit status, $0: Script name, $$: Script's process ID.
Question-18. How do you use arithmetic operations in Bash?
Answer-18: Use $((expression)). Example: result=$((a + b)).
Question-19. How do you check if a file exists in Bash?
Answer-19: Use [ -e filename ].
Question-20. How do you append text to a file in Bash?
Answer-20: Use >>. Example: echo "text" >> file.txt.
Question-21. What is a function in Bash?
Answer-21: A reusable block of code defined using function name { commands; }.
Question-22. How do you call a function in Bash?
Answer-22: Use the function name followed by parentheses. Example: myFunction.
Question-23. What is the difference between > and >>?
Answer-23: > overwrites a file, while >> appends to a file.
Question-24. What is the purpose of grep?
Answer-24: grep searches for patterns in files or outputs. Example: grep "pattern" file.
Question-25. How do you use case statements in Bash?
Answer-25: Example: case variable in pattern) commands ;; esac.
Question-26. How do you check the length of a string in Bash?
Answer-26: Use ${#string}. Example: length=${#mystring}.
Question-27. How do you split a string in Bash?
Answer-27: Use IFS and read. Example: IFS=',' read -r -a array <<< "$string".
Question-28. What is the difference between & and && in Bash?
Answer-28: & runs a command in the background, while && runs the next command only if the first succeeds.
Question-29. How do you create an array in Bash?
Answer-29: Use array=(element1 element2). Access with ${array[index]}.
Question-30. How do you find the length of an array in Bash?
Answer-30: Use ${#array[@]}. Example: length=${#array[@]}.
Question-31. What is the purpose of awk in shell scripting?
Answer-31: awk is used for text processing and data extraction.
Question-32. What does sed do in shell scripting?
Answer-32: sed is a stream editor for text manipulation. Example: sed 's/old/new/g' file.
Question-33. How do you trap signals in Bash?
Answer-33: Use the trap command. Example: trap "cleanup_function" SIGINT.
Question-34. How do you check if a directory exists?
Answer-34: Use [ -d directory_name ].
Question-35. What is the use of set -e in Bash?
Answer-35: set -e exits the script immediately if a command fails.
Question-36. What is the purpose of the export command?
Answer-36: export makes a variable available to child processes.
Question-37. How do you concatenate strings in Bash?
Answer-37: Use string1$string2. Example: fullstring="$string1$string2".
Question-38. What is the difference between . and source?
Answer-38: They are identical and are used to execute a script in the current shell.
Question-39. What is the eval command in Bash?
Answer-39: eval executes a string as a command. Example: eval "ls -l".
Question-40. How do you redirect both stdout and stderr to a file?
Answer-40: Use command > file 2>&1.
Question-41. How do you create a cron job for a shell script?
Answer-41: Use crontab -e to add a job. Example: 0 5 * * * /path/to/script.sh.
Question-42. How do you check if a variable is empty?
Answer-42: Use [ -z "$variable" ].
Question-43. What is the purpose of shift in shell scripting?
Answer-43: shift moves the positional parameters left.
Question-44. How do you declare a readonly variable in Bash?
Answer-44: Use readonly or declare -r. Example: readonly VAR="value".
Question-45. What is the use of ulimit in shell scripting?
Answer-45: ulimit sets resource limits for processes.
Question-46. How do you find the exit status of a command?
Answer-46: Use $?. Example: if [ $? -eq 0 ]; then ....
Question-47. What is the difference between hard and soft links?
Answer-47: Hard links point to the same inode, while soft links are shortcuts to a file.
Question-48. How do you check the running shell?
Answer-48: Use echo $SHELL.
Question-49. What does exec do in shell scripting?
Answer-49: exec replaces the current shell process with the specified command.
Question-50. How do you debug a Bash script?
Answer-50: Use bash -x scriptname.sh or add set -x in the script.
Frequently Asked Question and Answer on Shell Scripting Bash
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