103.2Basic
users.txt contains one user name per line.
Count the number of lines in the file.
Which command is correct?
× Incorrect
wc -l counts newline characters. For a conventional one-record-per-line file, this gives the line count.
Detailed explanation
Incorrect
wc -w users.txtIncorrect. -w counts words rather than lines.
Incorrect
wc -c users.txtIncorrect. -c counts bytes rather than lines.
Correct
wc -l users.txtCorrect. -l reports the number of newline characters.
Incorrect
nl users.txtIncorrect. nl numbers lines but does not return only the count.
Try it yourself
An example you can run in a temporary verification environment.
printf 'alice
bob
carol
' | wc -lExpected result
3（前の空白幅は環境により異なる）Key points
- wc aggregates input
- -l counts lines
- -w and -c count words and bytes
Notes
- Environment: GNU coreutils 9.x
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Read the scope first
Check whether the command acts on the current shell, a new process, an existing process, or a file.
Verify the observable result
Use the supplied command and compare the output with the expected result.
Question IDKP-103-034
EnvironmentGNU coreutils 9.x
Last technical review2026-08-12
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