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Question-1. How do you save changes to a file in sed?
Answer-1: Use the -i option, e.g., sed -i 's/foo/bar/' file.
Question-2. What does the -e option do in sed?
Answer-2: The -e option allows you to specify multiple commands in one sed command.
Question-3. How do you append a line after a match in sed?
Answer-3: Use the a command, e.g., sed '/pattern/a\new line' file.
Question-4. How do you insert a line before a match in sed?
Answer-4: Use the i command, e.g., sed '/pattern/i\new line' file.
Question-5. How do you delete empty lines in a file using sed?
Answer-5: Use sed '/^$/d' file.
Question-6. How do you match lines that start with a specific pattern?
Answer-6: Use ^ in the pattern, e.g., sed '/^foo/d' deletes lines starting with "foo".
Question-7. How do you match lines that end with a specific pattern?
Answer-7: Use $ in the pattern, e.g., sed '/bar$/d' deletes lines ending with "bar".
Question-8. How do you substitute only the first occurrence in a line?
Answer-8: This is the default behavior, e.g., sed 's/foo/bar/'.
Question-9. How do you substitute the nth occurrence in sed?
Answer-9: Use a number, e.g., sed 's/foo/bar/2' replaces the second occurrence in a line.
Question-10. How do you delete lines between two patterns?
Answer-10: Use sed '/start/,/end/d' file.
Question-11. How do you print the line number along with its content?
Answer-11: Use `sed = file
Question-12. What is the q command in sed?
Answer-12: The q command quits processing after a specified line, e.g., sed '5q' file.
Question-13. How do you replace tabs with spaces in sed?
Answer-13: Use sed 's/\t/ /g' file.
Question-14. How do you duplicate lines using sed?
Answer-14: Use the p command, e.g., sed '2p' file.
Question-15. How do you match a word boundary in sed?
Answer-15: Use \b, e.g., sed '/\bword\b/d'.
Question-16. How do you apply sed commands from a file?
Answer-16: Use sed -f script.sed file.
Question-17. What is the purpose of curly braces {} in sed?
Answer-17: Curly braces group commands for a pattern or range, e.g., sed '/pattern/{cmd1; cmd2}'.
Question-18. How do you replace a string on a specific line in sed?
Answer-18: Specify the line number, e.g., sed '3s/foo/bar/' file.
Question-19. How do you convert uppercase to lowercase in sed?
Answer-19: Use sed 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/' file.
Question-20. How do you convert lowercase to uppercase in sed?
Answer-20: Use sed 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/' file.
Question-21. What is the = command in sed?
Answer-21: The = command prints the line number.
Question-22. How do you remove trailing spaces using sed?
Answer-22: Use sed 's/[[:space:]]*$//' file.
Question-23. How do you remove leading spaces using sed?
Answer-23: Use sed 's/^[[:space:]]*//' file.
Question-24. How do you replace a pattern globally across the file?
Answer-24: Use the g flag, e.g., sed 's/foo/bar/g' file.
Question-25. How do you use backreferences in sed?
Answer-25: Use \1, \2, etc., e.g., sed 's/\(foo\)\(bar\)/\2\1/'.
Question-26. How do you remove duplicate lines in sed?
Answer-26: Use sed '$!N; /^\(.*\)\n\1$/!P; D'.
Question-27. How do you insert a blank line between lines using sed?
Answer-27: Use sed G file.
Question-28. How do you reverse a file using sed?
Answer-28: Use sed '1!G;h;$!d' file.
Question-29. How do you replace a string in a range of lines?
Answer-29: Use sed '2,4s/foo/bar/' file.
Question-30. How do you print lines that do not match a pattern?
Answer-30: Use sed -n '/pattern/!p' file.
Question-31. How do you delete lines matching a regular expression?
Answer-31: Use sed '/regex/d' file.
Question-32. How do you append text to the end of each line?
Answer-32: Use sed 's/$/text/' file.
Question-33. How do you handle multiple files in sed?
Answer-33: Specify multiple files, e.g., sed 's/foo/bar/' file1 file2.
Question-34. What is the ! operator in sed?
Answer-34: The ! operator negates a command, e.g., sed '/pattern/!d' deletes lines not matching the pattern.
Question-35. How do you delete lines with a specific length?
Answer-35: Use sed '/^.\{length\}$/d' file, e.g., sed '/^.\{10\}$/d' for lines of length 10.
Question-36. How do you comment out lines matching a pattern?
Answer-36: Use sed 's/^pattern/#&/' file.
Question-37. How do you replace text only on odd lines in sed?
Answer-37: Use sed '1~2s/foo/bar/' file.
Question-38. How do you replace text only on even lines in sed?
Answer-38: Use sed '2~2s/foo/bar/' file.
Question-39. What is sed?
Answer-39: sed is a stream editor used to perform basic text transformations on an input stream (a file or input from a pipeline).
Question-40. How does sed work?
Answer-40: sed reads input line by line, applies specified operations, and outputs the result.
Question-41. What is the basic syntax of sed?
Answer-41: sed 'command' file, where the command is an operation like substitution.
Question-42. How do you substitute text in sed?
Answer-42: Use s/old/new/, e.g., sed 's/foo/bar/' file.
Question-43. What does the -n option do in sed?
Answer-43: The -n option suppresses automatic printing, allowing only explicitly specified lines to be output.
Question-44. How do you print specific lines in sed?
Answer-44: Use p after the line number, e.g., sed -n '3p' file prints only the third line.
Question-45. What is a range in sed?
Answer-45: A range specifies a start and end line, e.g., sed '1,3d' file deletes lines 1 to 3.
Question-46. How do you delete lines in sed?
Answer-46: Use the d command, e.g., sed '2d' file deletes the second line.
Question-47. How do you replace all occurrences of a string in sed?
Answer-47: Use the g flag, e.g., sed 's/foo/bar/g' file.
Question-48. How do you specify a delimiter other than / in sed?
Answer-48: Use a different character, e.g., `sed 's
Question-49. How do you use sed with input from a pipeline?
Answer-49: Pipe the output to sed, e.g., `echo "foo"
Question-50. What does & represent in a substitution pattern?
Answer-50: & represents the matched string, e.g., sed 's/foo/&bar/' turns "foo" into "foobar".
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