Linux+ System Monitoring and Logging Flashcards

Which command displays real-time disk I/O statistics per process?

Answer: iotop

iotop shows real-time disk I/O usage per process, similar to how top shows CPU usage.

In journald, which option to journalctl shows only kernel messages?

Answer: -k

The -k flag (short for --dmesg) filters journalctl output to show only kernel ring buffer messages.

A sysadmin wants to monitor network bandwidth usage per interface in real time. Which tool is best suited?

Answer: nload

nload provides a real-time graphical display of network bandwidth usage per interface in the terminal.

What does the 'wa' field represent in the output of the top command?

Answer: CPU time spent waiting for I/O

The 'wa' field in top shows the percentage of CPU time spent idle while waiting for I/O operations to complete.

Which rsyslog directive sets the maximum log file size before rotation is triggered?

Answer: $outchannel with size limit

rsyslog's $outchannel directive can specify a size limit that triggers an action (such as rotation) when reached.

Which command shows the number of file descriptors currently open by all processes?

Answer: cat /proc/sys/fs/file-nr

The file /proc/sys/fs/file-nr contains three fields: allocated FDs, free FDs, and the system-wide maximum.

A log file is growing very quickly and consuming disk space. Which logrotate directive forces immediate rotation regardless of size?

Answer: size

The 'size' directive rotates the log file when it exceeds the specified size, regardless of the rotation schedule.