# htop

## NAME



           htop, pcp-htop - interactive process viewer
    


## SYNOPSIS



           **htop**[**-dCFhpustvH**]
           **pcp-htop**[**-dCFhpustvH**] [**--host/-h host**]
    


## DESCRIPTION



           **htop** is a cross-platform ncurses-based process viewer.
    
           It is similar to **top** , but allows you to scroll vertically and
           horizontally, and interact using a pointing device (mouse).  You
           can observe all processes running on the system, along with their
           command line arguments, as well as view them in a tree format,
           select multiple processes and act on them all at once.
    
           Tasks related to processes (killing, renicing) can be done without
           entering their PIDs.
    
           **pcp-htop** is a version of **htop** built using the Performance Co-Pilot
           (PCP) Metrics API (see PCPIntro(1), PMAPI(3)), allowing to extend
           **htop** to display values from arbitrary metrics.  See the section
           below titled **CONFIG FILES** for further details.
    


## COMMAND-LINE OPTIONS



           Mandatory arguments to long options are mandatory for short
           options too.
    
           **-d --delay=DELAY**
                  Delay between updates, in tenths of a second. If the delay
                  value is less than 1, it is increased to 1, i.e. 1/10
                  second. If the delay value is greater than 100, it is
                  decreased to 100, i.e. 10 seconds.
    
           **-C --no-color --no-colour**
                  Start **htop** in monochrome mode
    
           **-F --filter=FILTER**
                  Filter processes by terms matching the commands. The terms
                  are matched case-insensitive and as fixed strings (not
                  regexs). You can separate multiple terms with "|".
    
           **-h --help**
                  Display a help message and exit
    
           **-p --pid=PID,PID...**
                  Show only the given PIDs
    
           **-s --sort-key COLUMN**
                  Sort by this column (use --sort-key help for a column
                  list).  This will force a list view unless you specify -t
                  at the same time.  Sorting in tree mode applies to the
                  direct children of each process.
    
           **-u --user[=USERNAME|UID]**
                  Show only the processes of a given user, or self if omitted
    
           **-U --no-unicode**
                  Do not use unicode but ASCII characters for graph meters
    
           **-M --no-mouse**
                  Disable support of mouse control
    
           **--readonly**
                  Disable all system and process changing features
    
           **-V --version**
                  Output version information and exit
    
           **-t --tree**
                  Show processes in tree view. This can be used to force a
                  tree view when requesting a sort order with -s.
    
           **-H --highlight-changes=DELAY**
                  Highlight new and old processes
    
           **--drop-capabilities[=off|basic|strict]**
                  Linux only; this option needs to have been enabled at
                  compile-time and requires libcap support at runtime.
                  Drop unneeded Linux capabilities.  In strict mode features
                  like killing, changing process priorities and reading
                  process delay accounting information will not work due to
                  fewer capabilities being held.
    


## INTERACTIVE COMMANDS



           The following commands are supported while in **htop** :
    
           **Tab, Shift-Tab**
                Select the next / the previous screen tab to display.  You
                can enable showing the screen tab names in the Setup screen
                (F2).
    
           **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.
    
           **c** Tag the current process and its children. 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 or
                c keys).
    
           **s** Trace process system calls: if strace(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(1) is installed,
                pressing this key will display the list of file descriptors
                opened by the process.
    
           **w** Display the command line of the selected process in a
                separate screen, wrapped onto multiple lines as needed.
    
           **x** Display the active file locks of the selected process in a
                separate screen.
    
           **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, /**
                Incrementally search the command lines of all the displayed
                processes. The currently selected (highlighted) command will
                update as you type. While in search mode, pressing F3 will
                cycle through matching occurrences.  Pressing Shift-F3 will
                cycle backwards.
    
                Alternatively the search can be started by simply typing the
                command you are looking for, although for the first character
                normal key bindings take precedence.
    
           **F4, \**
                Incremental process filtering: type in part of a process
                command line and only processes whose names match will be
                shown. To cancel filtering, enter the Filter option again and
                press Esc.  The matching is done case-insensitive. Terms are
                fixed strings (no regex).  You can separate multiple terms
                with "|".
    
           **F5, t**
                Tree view: organize processes by parenthood, and layout the
                relations between them as a tree. Toggling the key will
                switch between tree and your previously selected sort view.
                Selecting a sort view will exit tree view.
    
           **F6, <, >**
                Selects a field for sorting, also accessible through < and >.
                The current sort field is indicated by a highlight in the
                header.
    
           **F7, ]**
                Increase the selected process's priority (subtract from
                'nice' value).  This can only be done by the superuser.
    
           **F8, [**
                Decrease the selected process's priority (add to 'nice'
                value)
    
           **Shift-F7, }**
                Increase the selected process's autogroup priority (subtract
                from autogroup 'nice' value).  This can only be done by the
                superuser.
    
           **Shift-F8, {**
                Decrease the selected process's autogroup priority (add to
                autogroup 'nice' value)
    
           **F9, k**
                "Kill" process: sends a signal which is selected in a menu,
                to one or a group of processes. If processes were tagged,
                sends the signal to all tagged processes.  If none is tagged,
                sends to the currently selected process.
    
           **F10, q**
                Quit
    
           **I** Invert the sort order: if sort order is increasing, switch to
                decreasing, and vice-versa.
    
           **+, -, ***
                When in tree view mode, expand or collapse subtree. When a
                subtree is collapsed a "+" sign shows to the left of the
                process name.  Pressing "*" will expand or collapse all
                children of PIDs without parents, so typically PID 1 (init)
                and PID 2 (kthreadd on Linux, if kernel threads are shown).
    
           **a (on multiprocessor machines)**
                Set CPU affinity: mark which CPUs a process is allowed to
                use.
    
           **u** Show only processes owned by a specified user.
    
           **N** Sort by PID.
    
           **M** Sort by memory usage (top compatibility key).
    
           **P** Sort by processor usage (top compatibility key).
    
           **T** Sort by time (top compatibility key).
    
           **F** "Follow" process: if the sort order causes the currently
                selected process to move in the list, make the selection bar
                follow it. This is useful for monitoring a process: this way,
                you can keep a process always visible on screen. When a
                movement key is used, "follow" loses effect.
    
           **K** Hide kernel threads: prevent the threads belonging the kernel
                to be displayed in the process list. (This is a toggle key.)
    
           **H** Hide user threads: on systems that represent them differently
                than ordinary processes (such as recent NPTL-based systems),
                this can hide threads from userspace processes in the process
                list. (This is a toggle key.)
    
           **O** Hide containerized processes: prevent processes running in a
                container from being displayed in the process list. (This is
                a toggle key.)
    
           **p** Show full paths to running programs, where applicable. (This
                is a toggle key.)
    
           **Z** Pause/resume process updates.
    
           **m** Merge exe, comm and cmdline, where applicable. (This is a
                toggle key.)
    
           **Ctrl-L**
                Refresh: redraw screen and recalculate values.
    
           **Numbers**
                PID search: type in process ID and the selection highlight
                will be moved to it.
    


## COLUMNS



           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).
    
                If the option 'Merge exe, comm and cmdline in Command'
                (toggled by the 'm' key) is active, the executable path
                (/proc/[pid]/exe) and the command name (/proc/[pid]/comm) are
                also shown merged with the command line, if available.
    
                The program basename is highlighted if set in the
                configuration. Additional highlighting can be configured for
                stale executables (cf. EXE column below).
    
                The Command column should be the last column in each screen
                as can get very long and profits from being able to extend
                its length dynamically.
    
           **COMM** The command name of the process obtained from
                /proc/[pid]/comm, if readable.
    
                Requires Linux kernel 2.6.33 or newer.
    
           **EXE** The abbreviated basename of the executable of the process,
                obtained from /proc/[pid]/exe, if readable. htop is able to
                read this file on linux for ALL the processes only if it has
                the capability CAP_SYS_PTRACE or root privileges.
    
                The basename is marked in red if the executable used to run
                the process has been replaced or deleted on disk since the
                process started. The information is obtained by processing
                the contents of /proc/[pid]/exe.
    
                Furthermore the basename is marked in yellow if any library
                is reported as having been replaced or deleted on disk since
                it was last loaded. The information is obtained by processing
                the contents of /proc/[pid]/maps.
    
                When deciding the color the replacement of the main
                executable always takes precedence over replacement of any
                other library. If only the memory map indicates a replacement
                of the main executable, this will show as if any other
                library had been replaced or deleted.
    
                This additional color markup can be configured in the
                "Display Options" section of the setup screen.
    
                Displaying EXE requires CAP_SYS_PTRACE and
                PTRACE_MODE_READ_FSCRED.
    
           **PID** The process ID.
    
           **STATE (S)**
                The state of the process:
                   **S** for sleeping
                   **I** for idle (longer inactivity than sleeping on platforms
                that distinguish)
                   **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** 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_VIRT (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_SWAP (SWAP)**
                The size of the process's swapped pages.
    
           **M_PSS (PSS)**
                The proportional set size, same as M_RESIDENT but each page
                is divided by the number of processes sharing it.
    
           **M_M_PSSWP (PSSWP)**
                The proportional swap share of this mapping, unlike M_SWAP
                this does not take into account swapped out page of
                underlying shmem objects.
    
           **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.  This is the default way to represent CPU usage in
                Linux. Each process can consume up to 100% which means the
                full capacity of the core it is running on. This is sometimes
                called "Irix mode" e.g. in top(1).
    
           **PERCENT_NORM_CPU (NCPU%)**
                The percentage of the CPU time that the process is currently
                using normalized by CPU count. This is sometimes called
                "Solaris mode" e.g. in top(1).
    
           **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.
    
                On Linux the username is highlighted if the process has
                elevated privileges, i.e. if it has been started from
                binaries with file capabilities set or retained Linux
                capabilities, via the ambient set, after switching from the
                root user.
    
           **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 Light-Weight Processes (=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(2) syscalls for the process.
    
           **SYSCW (WR_SYSC)**
                The number of write(2) syscalls for the process.
    
           **RBYTES (IO_RBYTES)**
                Bytes of read(2) I/O for the process.
    
           **WBYTES (IO_WBYTES)**
                Bytes of write(2) I/O for the process.
    
           **CNCLWB (IO_CANCEL)**
                Bytes of cancelled write(2) I/O.
    
           **IO_READ_RATE (DISK READ)**
                The I/O rate of read(2) in bytes per second, for the process.
    
           **IO_WRITE_RATE (DISK WRITE)**
                The I/O rate of write(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. For a shortened view see the
                CCGROUP column below.
    
           **CCGROUP**
                Shortened view of the cgroup name that the process is in.
                This performs some pattern-based replacements to shorten the
                displayed string and thus condense the information.
                   **/*.slice** is shortened to **/[*]**(exceptions below)
                   **/system.slice** is shortened to **/[S]**
                   **/user.slice** is shortened to **/[U]**
                   **/user-*.slice** is shortened to **/[U:*]**(directly preceding
                **/[U]** before dropped)
                   **/machine.slice** is shortened to **/[M]**
                   **/machine-*.scope** is shortened to **/[SNC:*]**(SNC: systemd
                nspawn container), uppercase for the monitor
                   **/lxc.monitor.*** is shortened to **/[LXC:*]**
                   **/lxc.payload.*** is shortened to **/[lxc:*]**
                   **/*.scope** is shortened to **/!***
                   **/*.service** is shortened to **/***(suffix removed)
    
                Encountered escape sequences (e.g. from systemd) inside the
                cgroup name are not decoded.
    
           **OOM** OOM killer score.
    
           **CTXT** Incremental sum of voluntary and nonvoluntary context
                switches.
    
           **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.
    
           **AGRP** The autogroup identifier for the process. Requires Linux CFS
                to be enabled.
    
           **ANI** The autogroup nice value for the process autogroup. Requires
                Linux CFS to be enabled.
    
           **All other flags**
                Currently unsupported (always displays '-').
    


## EXTERNAL LIBRARIES



           While **htop** depends on most of the libraries it uses at build time
           there are two noteworthy exceptions to this rule. These exceptions
           both relate to data displayed in meters displayed in the header of
           **htop** and were intentionally created as optional runtime
           dependencies instead.  These exceptions are described below:
    
           **libsystemd**
                  The bindings for libsystemd are used in the SystemD meter
                  to determine the number of active services and the overall
                  system state. Looking for the functions to determine these
                  information at runtime allows for builds to support these
                  meters without forcing the package manager to install these
                  libraries on systems that otherwise don't use systemd.
    
                  Summary: no build time dependency, optional runtime
                  dependency on **libsystemd** via dynamic loading, with
                  systemctl(1) fallback.
    
           **libsensors**
                  The bindings for libsensors are used for the CPU
                  temperature readings in the CPU usage meters if displaying
                  the temperature is enabled through the setup screen. In
                  order for **htop** to show these temperatures correctly though,
                  a proper configuration of libsensors through its usual
                  configuration files is assumed and that all CPU cores
                  correspond to temperature sensors from the **coretemp** driver
                  with core 0 corresponding to a sensor labelled "Core 0".
                  The package temperature may be given as "Package id 0". If
                  missing it is inferred as the maximum value from the
                  available per-core readings.
    
                  Summary: build time dependency on **libsensors**(3) C header
                  files, optional runtime dependency on **libsensors**(3) via
                  dynamic loading.
    


## CONFIG FILES



           By default **htop** reads its configuration from the XDG-compliant
           path _~/.config/htop/htoprc_.  The configuration file is overwritten
           upon clean exit by **htop** 's in-program Setup configuration, so it
           should not be hand-edited.  If no user configuration exists **htop**
           tries to read the system-wide configuration from
           _${prefix}/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).
    
           The **pcp-htop** utility makes use of _htoprc_ in a similar way.
           However, **pcp-htop** reads its configuration from a path more
           conventionally used by Performance Co-Pilot tools,
           _~/.pcp/htop/htoprc_ , in order to provide separate configuration
           when both **htop** and **pcp-htop** are installed and in use.  **pcp-htop**
           supports additional configuration files below the same directory
           allowing new meters, columns and screen tabs to be added via the
           Setup screen (F2).  This displays additional Available Meters,
           Available Column and Screen Tabs for each meter, column or screen
           configuration file.
    
           These **pcp-htop** configuration files are read once at startup.  The
           format of these files is described in detail in the **pcp-htop**(5)
           manual page.
    
           This functionality makes available many thousands of Performance
           Co-Pilot metrics for display by **pcp-htop** , as well as the ability
           to display custom metrics added at individual sites.  Applications
           and services instrumented using the OpenMetrics format
           **https://openmetrics.io** can also be displayed by **pcp-htop** if the
           pmdaopenmetrics(1) component is configured.
    
           The configuration for both **htop** and **pcp-htop** is only saved when a
           clean exit is performed. Sending any signal will cause _all_
           _configuration changes to be lost._
    


## MEMORY SIZES



           Memory sizes in **htop** are displayed in a human-readable form.
           Sizes are printed in powers of 1024 using binary IEC units.  If no
           suffix is shown the units are implicitly K as in KiB (kibibyte, 1
           KiB = 1024 bytes).
    
           The decision to use this convention was made in order to conserve
           screen space and make memory size representations consistent
           throughout **htop** as allocations are granular to full memory pages
           (4 KiB for most platforms).
    


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