NAME

       watch - execute a program periodically, showing output fullscreen

SYNOPSIS

       watch [options] command

DESCRIPTION

       watch  runs command repeatedly, displaying its output and errors (the first screenfull).  This allows you
       to watch the program output change over time.  By default, command is run every 2 seconds and watch  will
       run until interrupted.

OPTIONS

       -b, --beep
              Beep if command has a non-zero exit.

       -c, --color
              Interpret ANSI color and style sequences.

       -C, --no-color
              Do not interpret ANSI color and style sequences.

       -d, --differences[=permanent]
              Highlight  the  differences  between  successive  updates.  If  the optional permanent argument is
              specified then watch will show all changes since the first iteration.

       -e, --errexit
              Freeze updates on command error, and exit after a key press.

       -g, --chgexit
              Exit when the visible output of command changes. Changes that are off  the  screen  due  to  small
              screen size or large output will not cause watch to exit.

       -n, --interval seconds
              Specify  update  interval.   The command will not allow quicker than 0.1 second interval, in which
              the smaller values are converted. Both '.' and  ','  work  for  any  locales.  The  WATCH_INTERVAL
              environment  can  be used to persistently set a non-default interval (following the same rules and
              formatting).

       -p, --precise
              Make watch attempt to run command every --interval seconds.  Try it with ntptime (if present)  and
              notice  how  the  fractional seconds stays (nearly) the same, as opposed to normal mode where they
              continuously increase.

       -q, --equexit <cycles>
              Exit when output of command does not change for the given number of cycles.

       -r, --no-rerun
              Do not run the program on terminal resize, the output of the program will re-appear  at  the  next
              regular run time.

       -t, --no-title
              Turn  off the header showing the interval, command, and current time at the top of the display, as
              well as the following blank line.

       -w, --no-wrap
              Turn off line wrapping. Long lines will be truncated instead of wrapped to the next line.

       -x, --exec
              Pass command to exec(2) instead of sh -c which reduces the need to use extra quoting  to  get  the
              desired effect.

       -h, --help
              Display help text and exit.

       -v, --version
              Display version information and exit.

EXIT STATUS

              0      Success.
              1      Various failures.
              2      Forking the process to watch failed.
              3      Replacing child process stdout with write side pipe failed.
              4      Command execution failed.
              5      Closing child process write pipe failed.
              7      IPC pipe creation failed.
              8      Getting child process return value with waitpid(2) failed, or command exited up on error.
              other  The watch will propagate command exit status as child exit status.

ENVIRONMENT

       The behavior of watch is affected by the following environment variables.

       WATCH_INTERVAL
              Update interval, follows the same rules as the --interval command line option.

NOTES

       POSIX  option  processing is used (i.e., option processing stops at the first non-option argument).  This
       means that flags after command don't get interpreted by watch itself.

BUGS

       Upon terminal resize, the screen will not be correctly repainted until the next  scheduled  update.   All
       --differences highlighting is lost on that update as well. When using the --no-rerun option, no output of
       will be visible.

       Non-printing  characters are stripped from program output.  Use cat -v as part of the command pipeline if
       you want to see them.

       Combining Characters that are supposed to display on the character at the last column on the  screen  may
       display one column early, or they may not display at all.

       Combining Characters never count as different in --differences mode.  Only the base character counts.

       Blank lines directly after a line which ends in the last column do not display.

       --precise  mode doesn't yet have advanced temporal distortion technology to compensate for a command that
       takes more than --interval seconds to execute.  watch also can get into a state where it  rapid-fires  as
       many  executions  of  command  as  it  can  to  catch  up  from a previous executions running longer than
       --interval (for example, netstat(8) taking ages on a DNS lookup).

EXAMPLES

       To watch for mail, you might do
              watch -n 60 from
       To watch the contents of a directory change, you could use
              watch -d ls -l
       If you're only interested in files owned by user joe, you might use
              watch -d 'ls -l | fgrep joe'
       To see the effects of quoting, try these out
              watch echo $$
              watch echo '$$'
              watch echo "'"'$$'"'"
       To see the effect of precision time keeping, try adding -p to
              watch -n 10 sleep 1
       You can watch for your administrator to install the latest kernel with
              watch uname -r
       (Note that -p isn't guaranteed to work across reboots, especially in the face of ntpdate (if present)  or
       other bootup time-changing mechanisms)

REPORTING BUGS

       Please send bug reports to procps@freelists.org

procps-ng                                          2024-07-19                                           WATCH(1)