which and whereis for commands in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the path of the 'ls' command using 'which'.

Linux CLI

which [1]

Drag options to blanks, or click blank then click option'

Aecho

Bpwd

Ccd

Dls

Attempts:

3 left

💡 Hint

Common Mistakes

Using commands like 'pwd' or 'cd' instead of 'ls' in the 'which' command.

Forgetting to put the command name after 'which'.

The 'which' command shows the full path of the executable for the given command name. Here, 'ls' is the command we want to find.

2fill in blank

medium

Complete the code to find all locations of the 'bash' command using 'whereis'.

Linux CLI

whereis [1]

Drag options to blanks, or click blank then click option'

Acat

Bls

Cbash

Dgrep

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'whereis' with commands other than 'bash' when the question asks for 'bash'.

Confusing 'which' and 'whereis' commands.

'whereis' locates the binary, source, and manual page files for a command. Here, we want to find all locations related to 'bash'.

3fill in blank

hard

Fix the error in the code to correctly find the path of the 'python3' command using 'which'.

Linux CLI

which [1]

Drag options to blanks, or click blank then click option'

Apython3

Bpython

Cpythn3

Dpython2

Attempts:

3 left

💡 Hint

Common Mistakes

Misspelling the command name as 'pythn3'.

Using 'python' or 'python2' when the question asks for 'python3'.

The correct command name is 'python3'. Misspelling it like 'pythn3' will cause an error or no output.

4fill in blank

hard

Fill both blanks to find the path of 'grep' using 'which' and all related files using 'whereis'.

Linux CLI

which [1] && whereis [2]

Drag options to blanks, or click blank then click option'

Agrep

Bls

Ccat

Dawk

Attempts:

3 left

💡 Hint

Common Mistakes

Using different command names after 'which' and 'whereis'.

Using unrelated commands like 'ls' or 'cat' instead of 'grep'.

Both commands need the same command name 'grep' to find its path and related files.

5fill in blank

hard

Fill all three blanks to create a script that finds the path of a command stored in variable 'cmd' using 'which', then finds all related files using 'whereis'.

Linux CLI

cmd='[1]'
which [2]
whereis [3]

Drag options to blanks, or click blank then click option'

Anano

B$cmd

Dls

Attempts:

3 left

💡 Hint

Common Mistakes

Not using the variable 'cmd' in the 'which' and 'whereis' commands.

Assigning the wrong command name to 'cmd'.

The variable 'cmd' is assigned the command name 'nano'. Then 'which $cmd' and 'whereis $cmd' use the variable 'cmd' to find paths and related files.

Practice

1. What does the which command do in Linux?

easy

A. Lists all files related to a command including source and man pages

B. Displays the manual pages of a command

C. Shows the full path of the executable that runs when you type a command

D. Shows the current directory contents

Solution

1. Step 1: Understand the purpose of which

   The which command searches your PATH environment to find the executable file that runs when you enter a command.

2. Step 2: Compare with other options

   whereis lists multiple locations including source and man files, not just the executable path. Manual pages are shown by man. Directory contents are shown by ls.

3. Final Answer:

   Shows the full path of the executable that runs when you type a command -> Option C

4. Quick Check:

   which = executable path [OK]

Hint: Remember: which = executable path only [OK]

Common Mistakes:

• Confusing which with whereis
• Thinking which shows manual pages
• Assuming which lists all related files

2. Which of the following is the correct syntax to find the location of the ls command using which?

easy

A. which -l ls

B. which ls

C. which --all ls

D. which ls -a

Solution

1. Step 1: Recall basic which syntax

   The basic syntax to find the path of a command is simply which command_name. No extra flags are needed for a single path.

2. Step 2: Analyze options

   Options like -l or --all are not standard or needed for basic usage. Adding -a or extra flags incorrectly after the command name is invalid.

3. Final Answer:

   which ls -> Option B

4. Quick Check:

   Simple syntax: which + command [OK]

Hint: Use just 'which command' to find executable path [OK]

Common Mistakes:

• Adding unnecessary flags to which
• Placing flags after command name
• Using incorrect or unsupported options

3. What will be the output of the command whereis bash on a typical Linux system?

medium

A. bash: /bin/bash /usr/share/man/man1/bash.1.gz

B. bash: command not found

C. /usr/bin/bash

D. /bin/bash

Solution

1. Step 1: Understand whereis output format

   whereis shows multiple locations: the binary executable path, source files if any, and manual page locations.

2. Step 2: Analyze typical output for bash

   On most systems, whereis bash returns the binary path like /bin/bash and the man page location like /usr/share/man/man1/bash.1.gz.

3. Final Answer:

   bash: /bin/bash /usr/share/man/man1/bash.1.gz -> Option A

4. Quick Check:

   whereis = binary + man files [OK]

Hint: whereis shows binary and man page locations [OK]

Common Mistakes:

• Expecting only one path from whereis
• Confusing whereis output with which output
• Thinking whereis returns error if command exists

4. You run which python3 but get no output. What is the most likely reason?

medium

A. Python3 is installed but hidden by a firewall

B. You typed the command incorrectly

C. which command is broken on your system

D. Python3 is not installed or not in your PATH

Solution

1. Step 1: Interpret empty output from which

   If which returns nothing, it means it did not find the executable in any directory listed in your PATH environment variable.

2. Step 2: Consider common causes

   Most often, this means the program is not installed or its executable directory is not in PATH. Typing errors usually cause an error message, not empty output. The command itself rarely breaks, and firewalls do not hide executables.

3. Final Answer:

   Python3 is not installed or not in your PATH -> Option D

4. Quick Check:

   No output from which = command missing or PATH issue [OK]

Hint: No output means command not found in PATH [OK]

Common Mistakes:

• Assuming which is broken
• Blaming firewall for missing executable
• Ignoring PATH environment variable

5. You want to find all locations related to the gcc compiler including binary, source, and manual files. Which command should you use?

hard

A. whereis gcc

B. which gcc

C. locate gcc

D. find / -name gcc

Solution

1. Step 1: Understand the purpose of each command

   which shows only the executable path. locate searches a database for filenames but may show unrelated files. find searches the entire filesystem but is slow and may produce too many results.

2. Step 2: Identify the command that shows binary, source, and manual files

   whereis is designed to show all related locations for a command including binary, source, and man pages, making it the best choice.

3. Final Answer:

   whereis gcc -> Option A

4. Quick Check:

   whereis = binary + source + man files [OK]

Hint: Use whereis to find all related command files [OK]

Common Mistakes:

• Using which to find all files
• Using locate without filtering results
• Running find without knowing its slowness