MCQs on Performance Optimization | Shell Scripting
Enhance your shell scripting skills with these 30 MCQs on Performance Optimization. Learn how to measure script performance, parallelize tasks with xargs and &, and optimize logic for better efficiency.
MCQs on Performance Optimization
Measuring Script Performance with time
- What does the time command in shell scripting do?
a) Executes a command and measures the time taken
b) Sets the system time
c) Times the execution of a script only
d) Provides current time information - What is the output of the time command?
a) Time taken for the command to execute
b) Number of commands executed
c) Number of files modified
d) CPU usage percentage - Which of the following is NOT included in the output of the time command?
a) Real time
b) User time
c) System time
d) Memory usage - How can you measure the execution time of a script called myscript.sh?
a) time myscript.sh
b) ./myscript.sh time
c) script time myscript.sh
d) time -s myscript.sh - What would you add to the time command to output results to a file?
a) time -o file.txt
b) time > file.txt
c) time >> file.txt
d) time -file file.txt - What is the default unit of time measured by the time command?
a) Milliseconds
b) Seconds
c) Minutes
d) Microseconds - How can you display the system time and user time in human-readable format when using time?
a) time -f “%U %S”
b) time -v
c) time -h
d) time -format “%U %S” - What does real time in the output of the time command indicate?
a) Time spent in user mode
b) Time spent in kernel mode
c) The total elapsed time for the command execution
d) The CPU time used during execution - How can you measure the execution time of a background task?
a) time &
b) time bg
c) time command &
d) background time command - What does the time command output when used on a command with no output?
a) It only shows time statistics
b) It shows an error message
c) It shows an empty output
d) It does not return anything
Parallelizing Tasks with xargs and &
- What is the function of xargs in shell scripting?
a) Executes commands in parallel
b) Converts input into arguments for a command
c) Redirects the output of a command to a file
d) Replaces variables in a script - How do you run a command in the background using &?
a) command &
b) command > &
c) command & bg
d) & command - What is the use of xargs -P option?
a) Specifies the maximum number of parallel jobs
b) Specifies the input delimiter
c) Replaces arguments in the command
d) Limits the number of arguments - How would you run a command with multiple arguments using xargs?
a) echo args | xargs command
b) command xargs args
c) xargs echo args
d) xargs command args - What does xargs -n do?
a) Limits the number of arguments passed to the command
b) Specifies the maximum parallel jobs
c) Reads input from a file
d) Sends output to multiple files - Which of the following will run command1 and command2 in parallel using &?
a) command1 & command2 &
b) command1; command2
c) command1 | command2
d) command1 && command2 - How do you run multiple commands in parallel using xargs?
a) echo args | xargs -P 4 command
b) xargs -P 4 args command
c) xargs command -P 4 args
d) echo args | xargs -n 4 command - Which option with xargs allows you to execute commands in parallel?
a) -P
b) -n
c) -i
d) -l - What does xargs do if you provide input from stdin?
a) It converts each line of input into a separate argument for the command
b) It runs the command without any arguments
c) It ignores the input
d) It deletes all the input - How can you run a task in the background and wait for it to finish before proceeding?
a) command & wait
b) command && wait
c) command; wait
d) wait command
Optimizing Script Logic
- Which of the following techniques can help optimize a shell script?
a) Minimize the number of loops
b) Use variables to store repetitive values
c) Use efficient commands like awk instead of multiple grep commands
d) All of the above - How can you avoid using multiple if statements in a shell script?
a) Use case statements
b) Use only while loops
c) Use for loops only
d) Combine if statements using logical operators - What is one way to improve the performance of a script that processes a large number of files?
a) Use find instead of ls to list files
b) Use echo instead of cat
c) Use xargs to pass filenames to commands
d) Use touch to modify file timestamps - Which technique can optimize script performance when working with large datasets?
a) Load data into memory only once
b) Process data in chunks
c) Avoid unnecessary loops
d) All of the above - How can you optimize a loop that iterates over a large set of files?
a) Use xargs to pass files to a command
b) Use a while loop instead of a for loop
c) Avoid using find with multiple conditions
d) Always store results in a file before processing - What is the purpose of profile commands in performance optimization?
a) Track system performance
b) Measure and optimize the script’s execution time
c) Display memory usage during script execution
d) Create backups of scripts - How can you reduce memory consumption in shell scripts?
a) Avoid using multiple temporary files
b) Process data using in-place editing tools
c) Minimize the use of global variables
d) All of the above - What is the best practice for optimizing a script that uses a large number of subprocesses?
a) Use fewer subprocesses by batching tasks
b) Redirect output to a file
c) Use wait to prevent race conditions
d) Increase the buffer size of the script - What command can you use to measure script execution time for specific blocks of code?
a) time
b) profile
c) stat
d) top - Which of the following tools helps to optimize shell scripts for performance?
a) shfmt
b) shellcheck
c) awk
d) all of the above
Answer Key
| Qno | Answer (Option with Text) |
|---|---|
| 1 | a) Executes a command and measures the time taken |
| 2 | a) Time taken for the command to execute |
| 3 | d) Memory usage |
| 4 | a) time myscript.sh |
| 5 | a) time -o file.txt |
| 6 | b) Seconds |
| 7 | b) time -v |
| 8 | c) The total elapsed time for the command execution |
| 9 | c) time command & |
| 10 | a) It only shows time statistics |
| 11 | b) Converts input into arguments for a command |
| 12 | a) command & |
| 13 | a) Specifies the maximum number of parallel jobs |
| 14 | a) echo args |
| 15 | a) Limits the number of arguments passed to the command |
| 16 | a) command1 & command2 & |
| 17 | a) echo args |
| 18 | a) -P |
| 19 | a) It converts each line of input into a separate argument for the command |
| 20 | a) command & wait |
| 21 | d) All of the above |
| 22 | a) Use case statements |
| 23 | c) Use xargs to pass filenames to commands |
| 24 | d) All of the above |
| 25 | a) Use xargs to pass files to a command |
| 26 | b) Measure and optimize the script’s execution time |
| 27 | d) All of the above |
| 28 | a) Use fewer subprocesses by batching tasks |
| 29 | a) time |
| 30 | d) all of the above |