The file list.txt holds one file name per line. For each name you need to run `mv <name> /archive/`, so the name from the input has to appear before the destination, not at the end of the command line. Which command line does that?
LPIC-1 Exam 101-500, objective 103. GNU and Unix commands medium
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How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct xargs -I {} mv {} /archive/ < list.txt
Correct. -I defines a replacement string; xargs substitutes each input line for {} wherever it occurs in the command, and runs one mv per line.
Not correct xargs mv /archive/ < list.txt
Wrong. Without a replacement string xargs appends the input words after the arguments you gave, producing `mv /archive/ name1 name2 ...`, which tries to move /archive/ into the last name.
Not correct xargs -n 1 mv /archive/ < list.txt
Wrong. -n 1 only limits each invocation to one input word; the word is still appended, giving `mv /archive/ name` for every line.
Not correct xargs -0 mv {} /archive/ < list.txt
Wrong. -0 tells xargs that its input is NUL-separated; it does not define a replacement string, so {} is passed to mv as a literal argument.
Why
By default xargs appends the words it reads to the end of the command it builds, which only suits commands whose variable operands come last. -I replstr (GNU also allows the older -i) puts the input where you want it and implies one input line per command invocation, so it is slower but positionally flexible. Note that -I also turns off splitting on blanks: the whole line becomes one argument.
Where this comes from
- Cited
- manual page xargs(1)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 103 and space the ones you get wrong.
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