TOP(1) BSD Reference Manual TOP(1)
top - display and update information about the top CPU processes
top [-bIinqSu] [-d count] [-o field] [-p pid] [-s time] [-U username] [number]
top displays the top processes on the system and periodically updates this information. If standard output is an intelligent terminal (see below) then as many processes as will fit on the terminal screen are displayed by default. Otherwise, a good number of them are shown (around 20). Raw CPU percentage is used to rank the processes. If number is given, then the top number processes will be displayed instead of the de- fault. top makes a distinction between terminals that support advanced capabili- ties and those that do not. This distinction affects the choice of de- faults for certain options. In the remainder of this document, an intelligent terminal is one that supports cursor addressing, clear screen, and clear to end of line. Conversely, a "dumb" terminal is one that does not support such features. If the output of top is redirected to a file, it acts as if it were being run on a dumb terminal. The options are as follows: -b Use batch mode. In this mode, all input from the terminal is ig- nored. Interrupt characters (such as '^C' and '^\') still have an effect. This is the default on a dumb terminal, or when the out- put is not a terminal. -d count Show only count displays, then exit. A display is considered to be one update of the screen. This option allows the user to select the number of displays to be shown before top automatical- ly exits. For intelligent terminals, no upper limit is set. The default is 1 for dumb terminals. -I Do not display idle processes. By default, top displays both ac- tive and idle processes. -i Use interactive mode. In this mode, any input is immediately read for processing. See the section on INTERACTIVE MODE for an expla- nation of which keys perform what functions. After the command is processed, the screen will immediately be updated, even if the command was not understood. This mode is the default when stan- dard output is an intelligent terminal. -n Use non-interactive mode. This is identical to batch mode. -o field Sort the process display area using the specified field as the primary key. The field name is the name of the column as seen in the output, but in lower case. The OpenBSD version of top sup- ports cpu, size, res, time, and pri. -p pid Show only the process pid. -q Renice top to -20 so that it will run faster. This can be used when the system is being very sluggish to improve the possibility of discovering the problem. This option can only be used by root. -S Show system processes in the display. Normally, system processes such as the pager and the swapper are not shown. This option makes them visible. -s time Set the delay between screen updates to time seconds. The value may be fractional, to permit delays of less than 1 second. The default delay between updates is 5 seconds. -U username Show only those processes owned by username. This option current- ly only accepts usernames and will not understand UID numbers. -u Do not take the time to map UID numbers to usernames. Normally, top will read as much of the password database as is necessary to map all the user ID numbers it encounters into login names. This option disables all that, while possibly decreasing execution time. The UID numbers are displayed instead of the names. Both count and number fields can be specified as infinite, indicating that they can stretch as far as possible. This is accomplished by using any proper prefix of the keywords infinity, maximum, or all. The default for count on an intelligent terminal is, in fact, infinity. The environment variable TOP is examined for options before the command line is scanned. This enables a user to set his or her own defaults. The number of processes to display can also be specified in the environment variable TOP. The options -I, -S, and -u are actually toggles. A second specification of any of these options will negate the first. Thus a user who has the environment variable TOP set to "-I" may use the command "top -I" to see idle processes.
When top is running in interactive mode, it reads commands from the ter- minal and acts upon them accordingly. In this mode, the terminal is put in CBREAK, so that a character will be processed as soon as it is typed. Almost always, a key will be pressed when top is between displays; that is, while it is waiting for time seconds to elapse. If this is the case, the command will be processed and the display will be updated immediately thereafter (reflecting any changes that the command may have specified). This happens even if the command was incorrect. If a key is pressed while top is in the middle of updating the display, it will finish the update and then process the command. Some commands require additional informa- tion, and the user will be prompted accordingly. While typing this infor- mation in, the user's erase and kill keys (as set up by the command stty(1)) are recognized, and a newline terminates the input. These commands are currently recognized (^L refers to control-L): h or ? Display a summary of the commands (help screen). ^L Redraw the screen. q Quit top. The following commands may not be available with overstrike terminals: C Toggle the display of process command line arguments. d Change the number of displays to show (prompt for new number). Remember that the next display counts as one, so typing "d1" will make top show one final display and then immediately exit. e Display a list of system errors (if any) generated by the last kill or renice command. I or i Toggle the display of idle processes. k Send a signal (TERM by default) to a list of processes. This acts similarly to the command kill(1). n or # Change the number of processes to display (prompt for new number). o Change the sorting order of the processes (prompt for order). Values are the same as for the -o flag, as detailed above. p Display a specific process (prompt for PID). If the PID specified is simply "+", then processes belonging to all users will be displayed. r Change the priority (the nice) of a list of processes (prompt for the new nice value and the list of PIDs, all separated by space). This acts similarly to the command renice(8). S Toggle the display of system processes. s Change the number of seconds to delay between displays (prompt for new number). u Display only processes owned by a specific username (prompt for username). If the username specified is simply "+", then processes belonging to all users will be displayed.
The top few lines of the display show general information about the state of the system, including the three load average numbers, the current time, the number of existing processes, the number of processes in each state (starting, running, idle, stopped, zombie, dead, and on processor), and a percentage of time spent in each of the processor states (user, nice, system, interrupt, and idle). It also includes information about physical and virtual memory allocation. The load average numbers give the number of jobs in the run queue averaged over 1, 5, and 15 minutes. The remainder of the screen displays information about individual processes. This display is similar in spirit to ps(1) but it is not ex- actly the same. The following fields are displayed: PID The process ID. USERNAME The name of the process's owner. UID Used instead of USERNAME if -u is specified. PRI The current priority of the process. NICE The nice amount (in the range -20 to 20). SIZE The total size of the process (the text, data, and stack segments). RES The current amount of resident memory. STATE The current state (one of start, run, sleep, stop, idle, zomb, dead, or onproc). On multi-processor systems, this is followed by a slash and the CPU number on which the process is bound. WAIT A description of the wait channel the process is sleeping on if it's asleep. TIME The number of system and user CPU seconds that the pro- cess has used. CPU The raw percentage of CPU usage and the default field on which the display is sorted. COMMAND The name of the command that the process is currently running. (If the process is swapped out, this column is enclosed by angle brackets.)
TOP User-configurable defaults for options.
/dev/kmem kernel memory /dev/mem physical memory /etc/passwd used to map user ID to name /bsd kernel image
kill(1), ps(1), stty(1), systat(1), mem(4), renice(8)
William LeFebvre, EECS Department, Northwestern University
As with ps(1), things can change while top is collecting information for an update. The picture it gives is only a close approximation to reality. MirOS BSD #10-current August 14, 1997 3
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