top (software)

Sample output of top on a Unix-like operating system.

top is a program found in many Unix-like operating systems. It produces an ordered list of running processes selected by user-specified criteria, and updates it periodically. Default ordering by CPU usage, and only the top CPU consumers shown (hence the name.) top shows how much processing power and memory are being used, as well as other information about the running processes. Some versions of top allow extensive customization of the display, such as choice of columns or sorting method.

top is useful for system administrators, as it shows which users and processes are consuming the most system resources at any given time.

On Solaris, the roughly equivalent program is prstat.

The ps program is similar to top, but instead produces a snapshot of processes taken at the time of invocation.

See also

• Htop
• nmon — a system monitor tool for the AIX and Linux operating systems.

External links

• Linux top home page (procps) and man page
• BSD top home page and man page
• Alternate top programs for Linux include atop (uses process accounting) and Htop