RHCSA Linux System Administration Flashcards

Which command searches for all SUID binaries on the entire filesystem?

Answer: find / -perm -4000 -type f 2>/dev/null

-perm -4000 matches files where the SUID bit is set regardless of other permission bits.

A cron job must run every 15 minutes. Which crontab expression is correct?

Answer: */15 * * * * /script.sh

*/15 in the minute field means 'every 15 minutes' (0, 15, 30, 45).

You need to configure autofs to automatically mount NFS shares under /misc. Which file controls the autofs master map?

Answer: /etc/auto.master

/etc/auto.master (or auto.master.d/) is the top-level map that points to indirect map files like /etc/auto.misc.

Which command checks and repairs an ext4 filesystem on /dev/sdb1 (must be unmounted)?

Answer: fsck.ext4 -y /dev/sdb1

fsck.ext4 -y automatically answers yes to all repair prompts; the filesystem must be unmounted first.

A process with PID 1234 is unresponsive. Which signal forcefully terminates it?

Answer: kill -9 1234

Signal 9 (SIGKILL) cannot be caught or ignored by the process and immediately terminates it.

Which command displays real-time I/O statistics per block device every 2 seconds?

Answer: iostat -xz 2

iostat -x shows extended statistics per device and -z suppresses devices with no activity; the interval is 2 seconds.

What is the purpose of the 'sticky bit' when set on a directory like /tmp?

Answer: Only the file owner or root can delete files within the directory

The sticky bit on a directory restricts deletion so that only the file's owner or root can remove it.