htop - interactive process viewer
**htop** **\[**\-dChusv\]
Htop is a free (GPL) ncurses-based process viewer for Linux.
It is similar to top, but allows you to scroll vertically and horizontally, so you can see
all the processes running on the system, along with their full command lines, as well as
viewing them as a process tree, selecting multiple processes and acting on them all at
once.
Tasks related to processes (killing, renicing) can be done without entering their PIDs.
Mandatory arguments to long options are mandatory for short options too.
**\-d** **\
Delay between updates, in tenths of seconds
**\-C** **\
Start htop in monochrome mode
**\-h** **\
Display a help message and exit
**\-p** **\
Show only the given PIDs
**\-s** **\
Sort by this column (use
**\-u** **\
Show only the processes of a given user
**\-v** **\
Output version information and exit
The following commands are supported while in htop:
**Up,** **Alt-k**
Select (highlight) the previous process in the process list. Scroll the list if
necessary.
**Down,** **Alt-j**
Select (highlight) the next process in the process list. Scroll the list if
necessary.
**Left,** **Alt-h**
Scroll the process list left.
**Right,** **Alt-l**
Scroll the process list right.
**PgUp,** **PgDn**
Scroll the process list up or down one window.
**Home** Scroll to the top of the process list and select the first process.
**End** Scroll to the bottom of the process list and select the last process.
**Ctrl-A,** **^**
Scroll left to the beginning of the process entry (i.e. beginning of line).
**Ctrl-E,** **$**
Scroll right to the end of the process entry (i.e. end of line).
**Space**
Tag or untag a process. Commands that can operate on multiple processes, like "kill",
will then apply over the list of tagged processes, instead of the currently
highlighted one.
**U** Untag all processes (remove all tags added with the Space key).
**s** Trace process system calls: if [strace](../man1/strace.1.html)(1) is installed, pressing this key will attach
it to the currently selected process, presenting a live update of system calls issued
by the process.
**l** Display open files for a process: if [lsof](../man1/lsof.1.html)(1) is installed, pressing this key will
display the list of file descriptors opened by the process.
**F1,** **h,** **?**
Go to the help screen
**F2,** **S**
Go to the setup screen, where you can configure the meters displayed at the top of
the screen, set various display options, choose among color schemes, and select which
columns are displayed, in which order.
**F3,** **
The following columns can display data about each process. A value of '-' in all the rows
indicates that a column is unsupported on your system, or currently unimplemented in htop.
The names below are the ones used in the "Available Columns" section of the setup screen.
If a different name is shown in htop's main screen, it is shown below in parenthesis.
**Command**
The full command line of the process (i.e. program name and arguments).
**PID** The process ID.
**STATE** **(S)**
The state of the process:
**S** for sleeping (idle)
**R** for running
**D** for disk sleep (uninterruptible)
**Z** for zombie (waiting for parent to read its exit status)
**T** for traced or suspended (e.g by SIGTSTP)
**W** for paging
**PPID** The parent process ID.
**PGRP** The process's group ID.
**SESSION** **(SID)**
The process's session ID.
**TTY\_NR** **(TTY)**
The controlling terminal of the process.
**TPGID**
The process ID of the foreground process group of the controlling terminal.
**MINFLT**
The number of page faults happening in the main memory.
**CMINFLT**
The number of minor faults for the process's waited-for children (see MINFLT above).
**MAJFLT**
The number of page faults happening out of the main memory.
**CMAJFLT**
The number of major faults for the process's waited-for children (see MAJFLT above).
**UTIME** **(UTIME+)**
The user CPU time, which is the amount of time the process has spent executing on the
CPU in user mode (i.e. everything but system calls), measured in clock ticks.
**STIME** **(STIME+)**
The system CPU time, which is the amount of time the kernel has spent executing
system calls on behalf of the process, measured in clock ticks.
**CUTIME** **(CUTIME+)**
The children's user CPU time, which is the amount of time the process's waited-for
children have spent executing in user mode (see UTIME above).
**CSTIME** **(CSTIME+)**
The children's system CPU time, which is the amount of time the kernel has spent
executing system calls on behalf of all the process's waited-for children (see STIME
above).
**PRIORITY** **(PRI)**
The kernel's internal priority for the process, usually just its nice value plus
twenty. Different for real-time processes.
**NICE** **(NI)**
The nice value of a process, from 19 (low priority) to -20 (high priority). A high
value means the process is being nice, letting others have a higher relative
priority. The usual OS permission restrictions for adjusting priority apply.
**STARTTIME** **(START)**
The time the process was started.
**PROCESSOR** **(CPU)**
The ID of the CPU the process last executed on.
**M\_SIZE** **(VIRT)**
The size of the virtual memory of the process.
**M\_RESIDENT** **(RES)**
The resident set size (text + data + stack) of the process (i.e. the size of the
process's used physical memory).
**M\_SHARE** **(SHR)**
The size of the process's shared pages.
**M\_TRS** **(CODE)**
The text resident set size of the process (i.e. the size of the process's executable
instructions).
**M\_DRS** **(DATA)**
The data resident set size (data + stack) of the process (i.e. the size of anything
except the process's executable instructions).
**M\_LRS** **(LIB)**
The library size of the process.
**M\_DT** **(DIRTY)**
The size of the dirty pages of the process.
**ST\_UID** **(UID)**
The user ID of the process owner.
**PERCENT\_CPU** **(CPU%)**
The percentage of the CPU time that the process is currently using.
**PERCENT\_MEM** **(MEM%)**
The percentage of memory the process is currently using (based on the process's
resident memory size, see M\_RESIDENT above).
**USER** The username of the process owner, or the user ID if the name can't be determined.
**TIME** **(TIME+)**
The time, measured in clock ticks that the process has spent in user and system time
(see UTIME, STIME above).
**NLWP** The number of threads in the process.
**TGID** The thread group ID.
**CTID** OpenVZ container ID, a.k.a virtual environment ID.
**VPID** OpenVZ process ID.
**VXID** VServer process ID.
**RCHAR** **(RD\_CHAR)**
The number of bytes the process has read.
**WCHAR** **(WR\_CHAR)**
The number of bytes the process has written.
**SYSCR** **(RD\_SYSC)**
The number of [read](../man2/read.2.html)(2) syscalls for the process.
**SYSCW** **(WR\_SYSC)**
The number of [write](../man2/write.2.html)(2) syscalls for the process.
**RBYTES** **(IO\_RBYTES)**
Bytes of [read](../man2/read.2.html)(2) I/O for the process.
**WBYTES** **(IO\_WBYTES)**
Bytes of [write](../man2/write.2.html)(2) I/O for the process.
**CNCLWB** **(IO\_CANCEL)**
Bytes of cancelled [write](../man2/write.2.html)(2) I/O.
**IO\_READ\_RATE** **(DISK** **READ)**
The I/O rate of [read](../man2/read.2.html)(2) in bytes per second, for the process.
**IO\_WRITE\_RATE** **(DISK** **WRITE)**
The I/O rate of [write](../man2/write.2.html)(2) in bytes per second, for the process.
**IO\_RATE** **(DISK** **R/W)**
The I/O rate, IO\_READ\_RATE + IO\_WRITE\_RATE (see above).
**CGROUP**
Which cgroup the process is in.
**OOM** OOM killer score.
**IO\_PRIORITY** **(IO)**
The I/O scheduling class followed by the priority if the class supports it:
**R** for Realtime
**B** for Best-effort
**id** for Idle
**PERCENT\_CPU\_DELAY** **(CPUD%)**
The percentage of time spent waiting for a CPU (while runnable). Requires
CAP\_NET\_ADMIN.
**PERCENT\_IO\_DELAY** **(IOD%)**
The percentage of time spent waiting for the completion of synchronous block I/O.
Requires CAP\_NET\_ADMIN.
**PERCENT\_SWAP\_DELAY** **(SWAPD%)**
The percentage of time spent swapping in pages. Requires CAP\_NET\_ADMIN.
**All** **other** **flags**
Currently unsupported (always displays '-').
By default htop reads its configuration from the XDG-compliant path [~/.config/htop/htoprc](file:~/.config/htop/htoprc)
should not be hand-edited. If no user configuration exists htop tries to read the system-
wide configuration from /etc/htoprc and as a last resort, falls back to its hard coded
defaults.
You may override the location of the configuration file using the $HTOPRC environment
variable (so you can have multiple configurations for different machines that share the
same home directory, for example).
Memory sizes in htop are displayed as they are in tools from the GNU Coreutils (when ran
with the --human-readable option). This means that sizes are printed in powers of 1024.
(e.g., 1023M = 1072693248 Bytes)
The decision to use this convention was made in order to conserve screen space and make
memory size representations consistent throughout htop.