What is the Windows analog of the Linux watch command?

Question

I'm looking for a Windows program/script/command line function that works like Linux's watch program.

watch periodically calls another program/whatever and shows the result, which is great for refreshing an output file or similar every second:

watch cat my-output.txt

or, more powerfully:

watch grep "fail" my-output.txt

I've looked for it in cygwin's library, but it doesn't seem to be present.

score 66 · Answer 1 · edited Dec 13 '17 at 19:34

66

Write your own. Let's say file watch.bat contains :

@ECHO OFF
:loop
  cls
  %*
  timeout /t 5 > NUL
goto loop

and call it via, for example:

watch echo test

will echo test every 5 seconds.

edited Dec 13 '17 at 19:34

Scott - Слава Україні

22,532

answered Sep 21 '10 at 11:43

harrymc

498,455

score 55 · Answer 2 · edited Dec 03 '21 at 15:57

55

Powershell has the while command. You can use it like in Linux:

while (1) {your_command; sleep 5}

Linux version:

while true; do your_command; sleep5; done

Others:

while ($true) {netstat -an | findstr 23560; sleep 5; date}

edited Dec 03 '21 at 15:57

phuclv

30,396
15
136
260

answered Sep 20 '13 at 15:02

Mikis

659
5
3

David Spillett · Accepted Answer · 2023-07-31T09:50:43.733

watch is available in Cygwin, in the procps-ng⁰ package as listed here (this info can be found via the package search on the website, here). I don't think this package is installed by the default cygwin setup, but it is one I usually select on new installs in order to have the watch command available.

The location of tools in packages typically match package names in Linux distributions (the package containing watch is procps on Debian and Ubuntu too) so if the Cygwin package search function fails you, info for/from Linux distributions may offer clues. In this example the exact naming is no longer the case, though searching for procps would find procps-ng.

--

^{[0] procps is now deprecated (as noted here and here), the original package stopped being maintained and a couple of distros forked it to apply pending patches. In some places it is still called procps but in others like cygwin the new name was used}

score 21 · Answer 4 · answered Jan 10 '17 at 09:29

21

A generic Windows command oneliner to accomplish this:

for /l %g in () do @( echo test & timeout /t 2 )

Replace "echo test" with the command you wish to run repeatedly.

answered Jan 10 '17 at 09:29

w1mb0r

311

ErikW · Answer 5 · 2019-04-30T15:12:20.087

11

It's a PowerShell one liner:

while ($true) { <your command here> | Out-Host; Sleep 5; Clear }

edited Apr 30 '19 at 15:12

answered Jan 09 '17 at 19:03

ErikW

211
2
4

score 9 · Answer 6 · edited Feb 02 '16 at 14:18

9

This is how I would do it in PowerShell:

while(1){ netstat -an|grep 1920;start-sleep -seconds 2;clear }

The condition while(1) is equivalent to while true, looping indefinitely.

edited Feb 02 '16 at 14:18

Ben N

42,308

answered Jun 04 '14 at 17:55

klaypigeon

91

score 8 · Answer 7 · edited Jun 12 '14 at 20:51

I wrote this little PowerShell module to do what you were looking for. Just put it in

C:\Users\[username]\Documents\WindowsPowerShell\Modules\Watch

and run import-module watch in PowerShell.

# ---- BEGIN SCRIPT
# Author:       John Rizzo
# Created:      06/12/2014
# Last Updated: 06/12/2014
# Website:      http://www.johnrizzo.net

function Watch {
    [CmdletBinding(SupportsShouldProcess=$True,ConfirmImpact='High')]
    param (
        [Parameter(Mandatory=$False,
                   ValueFromPipeline=$True,
                   ValueFromPipelineByPropertyName=$True)]
        [int]$interval = 10,

        [Parameter(Mandatory=$True,
                   ValueFromPipeline=$True,
                   ValueFromPipelineByPropertyName=$True)]
        [string]$command
    )
    process {
        $cmd = [scriptblock]::Create($command);
        While($True) {
            cls;
            Write-Host "Command: " $command;
            $cmd.Invoke();
            sleep $interval;
        }
    }
}

Export-ModuleMember -function Watch

# --- END SCRIPT

score 3 · Answer 8 · answered Sep 21 '10 at 11:56

3

You can also make up a delay using the PING command, for example:

@echo off
:loop
  cls
  dir c:\temp
  REM 5000mS (5 sec) delay...
  ping 1.1.1.1 -n 1 -w 5000 >NUL
goto loop

answered Sep 21 '10 at 11:56

Linker3000

28,240

score 2 · Answer 9 · answered Jan 29 '16 at 13:44

2

I created a watch command for windows called llwatch.

The code is both on my website landenlabs.com

and also on GitHub

You may need to use x64 to watch x64 programs and x32 for the others. Not sure how picky windows is.

answered Jan 29 '16 at 13:44

LanDenLabs

131

score 2 · Answer 10 · answered Mar 16 '14 at 01:56

I had the same issue when needing to check the file size of a file actively being worked on by another process. I ended up cloning the functionality of watch on Windows. The compiled exe as well as the source is available at the site.

watch for Windows

score 1 · Answer 11 · answered Apr 14 '16 at 04:16

1

what @harrymc said except with sleep watch.bat

@ECHO OFF
:loop
  %*
  sleep 5
goto loop

./watch.bat npm run test

npm run test every 5 sec

answered Apr 14 '16 at 04:16

user2167582

305

Giovanni Patruno · Answer 12 · 2021-12-03T15:43:59.280

1

You can use this command in windows cmd (not working in powershell):

for /l %g in () do @( <your-command> & timeout /t 1 > nul )

The /t value is in seconds

This prevent the timeout command to write "Waiting for n seconds ..." so it's kind of silent.

If you want to go faster than 1 second you can do the following:

for /l %g in () do @( <your-command> & ping 127.0.0.1 -n 1 -w 500 > nul )

edited Dec 03 '21 at 15:43

answered Jun 09 '21 at 09:21

Giovanni Patruno

111

score 0 · Answer 13 · answered May 23 '18 at 16:36

0

PowerShell-Watch

Code Repository

answered May 23 '18 at 16:36

evandrix

123
1
4

score 0 · Answer 14 · answered Oct 30 '20 at 08:07

Some improvements on the excellent PS module written by johnrizzo1 (see here)

Renamed function to be in line with Powershell naming convention (as suggested by duct_tape_coder)
Moved interval to second argument, so it's optional; reduced default to 2 seconds
Fetch output of Invoke first, only then refresh the screen. This avoids the screen going blank while the command executes

function Watch-Command {
    [CmdletBinding(SupportsShouldProcess=$True,ConfirmImpact='High')]
    param (
        [Parameter(Mandatory=$True,
                   ValueFromPipeline=$True,
                   ValueFromPipelineByPropertyName=$True)]
        [string]$command,
    [Parameter(Mandatory=$False,
               ValueFromPipeline=$True,
               ValueFromPipelineByPropertyName=$True)]
    [int]$interval = 2
)
process {
    $cmd = [scriptblock]::Create($command);
    While($True) {
        $output = $cmd.Invoke();
        cls;
        Write-Host &quot;Command: &quot; $command;
        Write-Host ($output | Out-String);
        sleep $interval;
    }
}

}

score 0 · Answer 15 · edited Dec 18 '20 at 09:33

0

while(1) { clear; Command ;sleep 3; }

edited Dec 18 '20 at 09:33

Donald Duck is with Ukraine

2,629

answered Dec 18 '20 at 08:08

Hariharan S

11

score -1 · Answer 16 · answered Apr 19 '24 at 19:01

Here is the idiomatic PowerShell version of the excellent solution by @Wesley:

function Watch-Command {
    [CmdletBinding(ConfirmImpact = 'High')]
    param (
        [Parameter(Mandatory = $true, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
        [string]$Command,
    [Parameter(Mandatory = $false, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
    [int]$Interval = 2
)
process {
    $Cmd = [scriptblock]::Create($Command);
    while ($true) {
        $Output = $Cmd.Invoke();
        Clear-Host;
        Write-Host &quot;Command: &quot; $Command;
        Write-Host ($Output | Out-String);
        Start-Sleep -Seconds $Interval;
    }
}

}

score -2 · Answer 17 · edited Jan 10 '23 at 16:21

I was in a hurry.... I used one suggestion and changed it a little to work for me:

for /l %g in () do @( echo test & timeout /t 2 )

I changed it to:

for /l %g in () do @( test.bat & timeout /t 2 )

And I created the test.bat file with the command line. In my case, it was:

net group <NAME> /domain

I found that the echo command just printed out to the screen but did not execute the command

What is the Windows analog of the Linux watch command?

17 Answers17

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