Multiple choice technology operating systems

A user types history command and gets the following output 141 cd .tcs 142 ll tcs.lst 143 pwd 144 vi tcs.lst 145 ll -lrt | awk '{ print \$NF }' 146 echo "Test" 147 ps -ef | grep lsnr 148 grep a * 149 ls 150 echo \$PWD Refering to the scenario above, which one of the following is not a method for recovering the pwd command

  1. r 143

  2. fc -e -r p

  3. fc -e 143

  4. r -8

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To re-execute command 143 (pwd), valid methods are: r 143 (re-run by number), r -8 (re-run 8 commands back), and fc -s 143 (fix and run). The command 'fc -e -r p' (B) is syntactically problematic - 'fc -e' expects an editor name, and the flag combination doesn't constitute a valid re-execution method. This makes B the correct answer to 'which is NOT a valid method.'

AI explanation

In C-shell style history recall, r 143 re-executes event 143 directly, fc -e 143 invokes the fix-command editor on event 143, and r -8 recalls the command 8 events back from the current one (both landing on the pwd at line 143). fc -e -r p instead does a reversed pattern search for the most recent command starting with 'p', which would actually match the more recent ps -ef (147) rather than pwd (143), so it is not a reliable way to recover that specific command.

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