Challenge - 5 Problems
Permission Master
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Test your skills under time pressure!
💻 Command Output
intermediate1:30remaining
What is the permission string for mode 755?
You run
ls -l on a file with numeric permission mode 755. What is the permission string shown in the output?Attempts:
2 left
💡 Hint
Think about what each digit means: owner, group, others.
✗ Incorrect
Mode 755 means owner has read, write, execute (7), group has read and execute (5), others have read and execute (5). This corresponds to '-rwxr-xr-x'.
💻 Command Output
intermediate1:30remaining
What is the permission string for mode 644?
You set a file's permission to
644. What permission string will ls -l show?Attempts:
2 left
💡 Hint
Remember 6 means read and write, 4 means read only.
✗ Incorrect
Mode 644 means owner has read and write (6), group has read only (4), others have read only (4). This matches '-rw-r--r--'.
🚀 Application
advanced1:30remaining
Set permissions to 755 using chmod
You want to set a directory's permissions to
755. Which command will do this correctly?Attempts:
2 left
💡 Hint
755 means owner full, group and others read and execute.
✗ Incorrect
The numeric mode 755 sets owner to rwx, group and others to r-x. Option C uses the correct numeric mode.
💻 Command Output
advanced1:30remaining
What error occurs with invalid numeric mode 999?
You run
chmod 999 file.txt. What happens?Attempts:
2 left
💡 Hint
Numeric modes must be between 0 and 7 for each digit.
✗ Incorrect
Each digit in numeric mode must be 0-7. 9 is invalid, so chmod reports an invalid mode error.
🧠 Conceptual
expert2:00remaining
How many files have execute permission with mode 755 in a list?
You have 3 files with permissions set as: file1=755, file2=644, file3=700. How many files have execute permission for the owner?
Attempts:
2 left
💡 Hint
Check the owner's execute bit in each mode.
✗ Incorrect
755 owner has execute, 644 owner does not, 700 owner has execute. So 2 files have execute permission for owner.