Questions tagged [watch]

watch will execute a program periodically, displaying the output.

Filter by
Sorted by
Tagged with
-1 votes
1 answer
52 views

Watch command: Updates only periodically, not event-based? (Example: Every 2 seconds - every time file x gets saved)

What I'd like to have: Running a command y with watch command and have watch command update only as soon as output of command y has changed. Imagine a bash script with 3 lines of echo output Hello ...
futurewave's user avatar
-1 votes
2 answers
24 views

Linux "watch" command showing last 30 lines of nft list ruleset [duplicate]

I want to constantly see last 30 lines of code "nfc list ruleset" in Debian Bash. Something like this: watch -n 1 nft list ruleset | tail -n 30 But above code doesn't show last 30 lines of &...
gio's user avatar
  • 9
1 vote
1 answer
257 views

How can I get colored output of `systemd` commands run with `watch` inside xterm?

Somehow I'm unable to get this working with color output, it works but no colors are shown. I'm currently using these alias'es in my bash shell: alias Xterm='xterm -geometry 132x60 +dc +cm -e ' alias ...
Tripple Moon's user avatar
-1 votes
1 answer
64 views

How can I 'sudo watch sensors' and 'sudo docker stats' in one window on Ubuntu Server?

I tried watch 'sensors | sudo docker stats' sudo 'docker stats | watch sensors' sudo docker stats | sudo watch sensors So I assume its not possible to display both outputs in one window? Other than ...
cpitts88's user avatar
1 vote
1 answer
969 views

How to run bash function in "watch" command?

Say I have a function f defined in my bashrc function f() { date } I want to run following command to monitor the output watch f. The command failed with "sh: f: command not found". watch ...
user607722's user avatar
1 vote
0 answers
31 views

Do I have to write a shell script purely to access bash for loops inside of say watch? [duplicate]

I'd like to monitor apps that have inotify instance in real-time with watch using something similar to: watch "for foo in /proc/*/fd/*; do readlink -f $foo; done | grep inotify | sort | uniq -c | ...
Tomachi's user avatar
  • 111
1 vote
1 answer
72 views

`watch -n 100 'sh script.sh >> /path/to/output/output.txt` doesn't write to output.txt?

I'm currently executing the following: watch -n 100 'sh script.sh >> /path/to/output/output.txt' & It's been running for 30 minutes (I can verify with ps -ef | grep watch), however there's ...
student010101's user avatar
2 votes
1 answer
143 views

alias for watch command gets stopped?

I create this alias, so that aliases get expanded in the watch statement. > alias w='watch -x bash -i -c' > alias k=kubectl I execute it: > w 'k get pods; echo; k get svc' After two seconds ...
guettli's user avatar
  • 1,379
1 vote
0 answers
29 views

how to wrap command with many quotes into watch properly?

I have such a bash command ... psql -c "SELECT datname FROM pg_database WHERE datname LIKE 'efa%' OR datname LIKE 'geocms%';" and am wondering how to wrap this into watch -cd "<...
vrms's user avatar
  • 139
1 vote
1 answer
29 views

watch -n1 $() does not run $() every interval

watch -n1 $() does not update $(). what is the workaround? here is my example: watch -n1 echo $(( $(date +%s -d "sun") - $( date +%s ) )) this results in Every 1.0s: echo 106602 ...
stacking and exchanging woohoo's user avatar
0 votes
1 answer
299 views

terminal timer with end time given through bash

so I had the idea of making a bash function that takes in a time in hh:mm:ss (24 hour format) and makes a timer till that time kinda like a one time alarm while also showing how much time is left I ...
stacking and exchanging woohoo's user avatar
2 votes
0 answers
105 views

Watch command -d=cumulative gives unexpected behavior with --color

This script gives the expected behavior, highlighting the parts of the date that change: watch -d=cumulative date However this script highlights the entirety of the text instead of just the things ...
Jake's user avatar
  • 21
3 votes
2 answers
211 views

How can I see the change that caused watch -g to exit

I'm using watch -g to monitor the output of a command and exit as soon as it changes. The problem is that all the UI elements of watch (including the output of the command that I'm monitoring) ...
Ryan's user avatar
  • 31
1 vote
0 answers
124 views

watch a whole directory and print diff on file change

Is there a way to easily watch a full directory for changes and print a diff when a file changed? Context: I would like to discover the name of the options in KDE Plasma's configuration by watching ....
tobiasBora's user avatar
  • 3,981
3 votes
1 answer
2k views

Getting "Segmentation fault (core dumped)" every time I try to run `watch` with `nvidia-smi`

I'm currently using GPUs on an Ubuntu server to run machine learning models. I often like to use the watch command in order to monitor the GPU statuses like watch -n 1 nvidia-smi. It usually works ...
Sean's user avatar
  • 171
1 vote
1 answer
203 views

How to use alias to a watch command which include another alias and some double and single quotes in the latter alias?

alias vov="scontrol -o show nodes | grep -e \"-lkeb\" -e \"-gpu\"| awk '{ printf(\"%-15s%-9s%-7s%-18s%-11s%-9s%s\n\", substr(\$1, 10), substr(\$4, 10), substr(\$5, ...
Jingnan Jia's user avatar
0 votes
2 answers
133 views

Kubuntu: how to disable color in output of 'watch' command

I am runnung Kubuntu 20.04. Command watch is from package procps. dpkg -l procps shows the version: 2:3.3.16-1ubuntu2 I am redirecting the output of warch to a file, like watch -t "date" &...
Anton Wessel's user avatar
2 votes
2 answers
678 views

Why doesn't watch bash -c '"echo $RANDOM"' print anything?

I expect this command to print a random value to the screen every 2 seconds, but instead it doesn't print anything: watch bash -c '"echo $RANDOM"' This command, however, does print a random ...
Adrian's user avatar
  • 179
3 votes
1 answer
428 views

How to tackle leaking file watchers on Debian 11?

I work with a couple different nodejs live servers as part of my job and there seems to be some kind of leak within my tooling/workflow causing file watchers to accumulate over time until they hit the ...
mkurz's user avatar
  • 197
3 votes
3 answers
838 views

Scrollable version of `watch`

We need to track a status file that is rewritten every few seconds by a server process. The watch command works beautifully for this (i.e. watch cat file.txt), except now the table is several pages ...
Hephaestus's user avatar
1 vote
2 answers
851 views

watch command displays different ps results than when running script by itself

Here's my script: $ cat count_tomcat.sh ps -ef | grep tomcat| wc -l $ ./count_tomcat.sh 2 Now with the watch command it has different results: $ watch ./count_tomcat.sh Every 2.0s: ./count_tomcat....
rogerdpack's user avatar
  • 1,715
0 votes
2 answers
42 views

`watch` a PostgreSQL query without displaying the full connection string

I'd like to share online, with team members, some live modifications on a PostgreSQL database (hosted on a dockerized Debian Bullseye) using watch (if you know any other tool, preferably pgAdmin4 but ...
s.k's user avatar
  • 431
0 votes
1 answer
172 views

Get updated output when using watch

I use watch to monitor the progress of file conversions. watch -n 2 "echo Converted: $(ls *.mp3 | wc -l) of $(ls *.wav | wc -l) files" When using command substitutions using the $(command) ...
Moka's user avatar
  • 155
1 vote
2 answers
185 views

I can't wrap a command inside watch

I have this perfectly working command: netstat -tuplean | awk '{NR>1; if( $6 ~ /ESTABLISHED/ ) print "\033[0;31m" $5 " \033[01;31m"$6;if ($6 ~ /_WAIT/ ) print "\033[0;...
achille's user avatar
  • 203
10 votes
2 answers
1k views

ls formatting inside watch command

When I do ls /dev/tty*, I see the following output: /dev/tty /dev/tty12 /dev/tty17 /dev/tty21 /dev/tty26 /dev/tty30 /dev/tty35 /dev/tty4 /dev/tty44 /dev/tty49 /dev/tty53 /dev/tty58 /dev/...
red0ct's user avatar
  • 645
1 vote
2 answers
1k views

How to make backgrounded `watch` execute command on change

I wanna use watch on certain commands and files (e.g. w), having it run in the background and notify me of any change. I've tried the following: (watch -g cat tmp && echo "changed") &...
ChocolateOverflow's user avatar
1 vote
2 answers
2k views

How to watch a for-loop in bash?

Is it possible to use a for-loop with the watch command? I'm not really sure what to make of this error with what I've tried: $ for i in 1 2 3; do echo $i; done 1 2 3 $ watch -n 10 for i in 1 2 3; do ...
StoneThrow's user avatar
  • 1,707
0 votes
1 answer
449 views

Shell script error ONLY when using watch command

I'm trying to create a shell script that reads and writes to certain text files on two second intervals. When I run the script by itself (without watch), it works perfectly fine. However, when I run ...
Michael Kellam's user avatar
2 votes
1 answer
136 views

Observe command until output remains the same. Inverse of `watch -g`

Is there a possibility to watch a command until the output remains the same? With watch -g, one can check if a commands results changed and use this as a trigger to go to the next step in a script. ...
FelixJN's user avatar
  • 13.5k
1 vote
1 answer
458 views

Bright colors do not display in watch --color

Given the following python script to print colored text: for i in range(30, 100): print(f'\033[{i}m{i}\033[0m', end=' ') print() Running on bash displays bright ...
fishstik's user avatar
0 votes
1 answer
763 views

How to `watch` output of `xxd` or `hexdump` command?

My tool is wtiting binary chars to stdout and I can view it in hex with # ./md /dev/ttyUSB0 | xxd 0000000: 6f03 1100 0003 0084 8400 0000 0900 0a00 o............... 0000010: 0008 0004 0000 0000 2c00 ...
Dims's user avatar
  • 3,255
5 votes
1 answer
2k views

How to use aliases with `watch` command?

I have some bash aliases in my ~/.bashrc, but they're not available within a watch command. Normally, I would source ./some_script.sh which uses these aliases, but am having trouble figuring out how ...
tarabyte's user avatar
  • 4,276
0 votes
1 answer
5k views

watch tail -20 ls -ltr?

I would like to see the latest content of a directory. I tried watch tail -20 ls -ltr ./{directory} it is not working. Is there a way to constantly shows the content of a directory like watch command?
DGKang's user avatar
  • 121
0 votes
2 answers
258 views

watch without blank line

I want to execute a program periodically and watch when something changes. It sounds like watch would be the right command for that but it prints out annoying empty lines which makes it impossible to ...
12431234123412341234123's user avatar
2 votes
0 answers
736 views

Have watch exit, when the output does not change anymore

Is there a simple way to have watch cancel, if the output does NOT change anymore? watch -g will exit once the output changes, but I want the opposite. So watch the output as long as it is still ...
cmmnn's user avatar
  • 121
8 votes
1 answer
569 views

Why does watch not show anything on screen when invoked with timeout in an script?

When I run this script, it does not display the watch output on the screen, and does not timeout after 5s. § cat script.sh #!/bin/bash timeout 5s watch -n 1 ps This is what I see on the screen when I ...
sudocracy's user avatar
  • 221
1 vote
1 answer
901 views

how to repeatedly stop and restart a command

I'm trying to find a simple way to repeatedly restart a command after a certain time (let's say 10 seconds for the purpose of this question). For simplicity let's say the command in question is htop -...
flawr's user avatar
  • 135
1 vote
1 answer
2k views

Write only differences with watch -d command

I have to use watch in order to write in a file (doc.txt) the differences between a new version of a file and an older. I tried watch -t -d -n 10 "cat myfile.txt | tee doc.txt" but all myfile.txt's ...
Sarah's user avatar
  • 11
3 votes
1 answer
3k views

What is this : ^[3;J^[H^[2J?

I am on a Debian system fresh installed, logged in via ssh on /dev/pts/0, and have entered the following command watch -n 10 clear > /dev/pts/0 ; netstat -tupn 2>/dev/null | grep -v 3306 > /...
Max Muster's user avatar
0 votes
1 answer
138 views

Bug: `watch &` won't work within a script

I had the following script to alert me when someone sends me mail: cd /var/mail watch -g ls && cat end ./alert end would be a blank file; when I am going home, I would modify the end file ...
Alex's user avatar
  • 1,165
0 votes
0 answers
197 views

du displaying strange file size, seems to follow some awkward size count rule

I'm facing something I can't explain to myself on a CentOS 7 VM. I'm watching a log file which is growing at a ~100KBps rate. I have a watch calling du but the output is always a power of 2, like in ...
Benj's user avatar
  • 123
-2 votes
1 answer
366 views

Watch command linux

when executing watch command to check a bunch of errors, the window is not able to show the rest of the errors when it reaches a certain amount of rows. I want to be able to see all rows being ...
Hussein's user avatar
0 votes
0 answers
76 views

How to prevent tabulated outputs of functons being messed up when using 'watch' over ssh?

While ssh-ing into my server I want to be able to monitor for activity over certain port using netstat. Instead of running it manually I want to automate it with watch. While the command (sudo netstat ...
KubaFYI's user avatar
  • 113
0 votes
1 answer
40 views

watch to remember its last zero exit output

I run a process that takes lot of time. Time is not a problem actually but I would like to know how much RAM memory it requires. Process is already running so /usr/bin/time is not an option. I found ...
jangorecki's user avatar
1 vote
2 answers
284 views

How to invert 'watch -b'?

I'm trying to get my terminal to alert me with a simple bell once my domain registration has finished (is resolvable). From watch --help: Options: -b, --beep beep if command has a ...
Panki's user avatar
  • 6,604
8 votes
3 answers
1k views

How can I watch the 17th (or last, if less) line in files of a folder?

I'm currently using watch head -n 17 * which works, but also shows all lines up to the 17th. Basically, I would like to only show the last line for each file that is shown with my current approach. ...
Felix Dombek's user avatar
9 votes
1 answer
807 views

Explain why watch 'jobs' does not work but watch 'ps' work?

jobs is my favorite command to see my codes which are running in the background. In order to check for them dynamically, I tend to type watch 'jobs' which does not display anything. However watch '...
Many's user avatar
  • 257
1 vote
2 answers
2k views

Does the "watch" command put stress on a scheduler?

I have an account on a compute cluster which uses the SLURM scheduler. I have some jobs in the queue and I'm using the "watch" command to see their status: watch squeue -u myUserName Does constantly ...
Niagara Falls's user avatar
0 votes
1 answer
686 views

How to monitor if a binary has been executed with no additional tool?

I want to be able to tell if a certain executable is called on a ubunutu machine. The binary is to be called by a java process. I have no permission to install additional software. Here is what I ...
Anthony Kong's user avatar
0 votes
1 answer
137 views

output of watch several commands not clear

I am restoring a database backup on my server and i need to watch output of df -h and restore utility db2pd -utilities. I tried this: watch -n 2 "db2pd -utilities && df -h output(summarized): ...
BlackCrystal's user avatar