CompTIA XK0-006: CompTIA Linux+

Last checked October 22, 2026 against the official CompTIA exam page.

1. Question 1System Management

   A sysadmin needs to find every file under /var/log that is larger than 100 MB and was modified in the last 24 hours. Which command does this?

   1. Alocate --existing --limit 500 /var/log
   2. Bls -lh /var/log/ | grep -E '100M|1G'
   3. Cdu -ah --threshold=100M -d 1 /var/log
   4. Dfind /var/log -type f -size +100M -mtime -1
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   Correct answer: D

   find combines a size test (+100M means larger than 100 MB) with a modification-time test (-mtime -1 means within the last day). ls and du do not filter by both criteria, and locate uses a database that does not check modification time this way.

2. Question 2Security

   A sysadmin notices that a file in a shared directory can be deleted by any user, even though it is owned by another user. Which permission setting is most likely missing from the directory?

   1. AThe sticky bit
   2. BThe setgid bit on the file
   3. CExecute permission on the file
   4. DThe setuid bit on the file
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   Correct answer: A

   The sticky bit on a directory restricts deletion so that only the file owner, the directory owner or root can remove files, which is the typical protection for shared directories such as /tmp. The setuid and setgid bits affect execution and group inheritance, and execute permission does not control deletion.

3. Question 3Scripting, Containers, and Automation

   A Bash script must stop at the first failing command and treat use of an unset variable as an error. Which shell options provide this behaviour?

   1. Aexport PATH=/usr/bin
   2. Bset -x only
   3. Cset -eu
   4. Dchmod +x script.sh
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   Correct answer: C

   set -e exits when a command fails and set -u treats unset variables as errors, which makes scripts fail fast and predictably. set -x only traces commands, exporting PATH changes the search path, and chmod affects permissions rather than error handling.

4. Question 4Troubleshooting

   A server is slow, and the administrator suspects heavy disk I/O. Which two tools help identify the cause? (Choose two.)

   1. Aip addr show
   2. Bnmcli connection up
   3. Ciotop or pidstat -d to see which processes are doing I/O
   4. Dhostnamectl set-hostname
   5. Eiostat from the sysstat package
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   Correct answer: C, E

   iostat reports device utilization and wait times, and iotop or pidstat -d show per-process I/O, which together locate the source. Address, connection and hostname commands do not measure disk activity.

5. Question 5System Management

   A server's root filesystem is 95 percent full. The administrator wants to see which top-level directories use the most space without crossing into other mounted filesystems. Which command is most suitable?

   1. Acat -n /etc/fstab
   2. Bdu -shx /* | sort -h
   3. Clsblk -o NAME,SIZE
   4. Dmount -av -t ext4
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   Correct answer: B

   du with -x stays on one filesystem, and sort -h orders the human-readable sizes so the largest directories appear last. fstab lists configured mounts, mount -a mounts them, and lsblk shows block devices rather than per-directory usage.