I installed tomcat9 on my EC2 server using commands sudo su yum install tomcat9 Then I tried running the command: /usr/sbin/tomcat9 start Then the error message is: Failed to start tomcat.service: Unit tomcat.service not found. Am I missing anything? What file is tomcat.service? Where do I need to create it? What does it contain? sudo tee /etc/systemd/system/tomcat.service 5月 16 16:08:18 ip-172-31-25-139.us-west-2.compute.internal systemd: tomcat.service: Failed at step EXEC spawning /usr/share/tomcat9/bin/catalina.sh: No such file or dire> 5月 16 16:08:18 ip-172-31-25-139.us-west-2.compute.internal systemd: tomcat.service: Control process exited, code=exited, status=203/EXEC 5月 16 16:08:18 ip-172-31-25-139.us-west-2.compute.internal systemd: tomcat.service: Failed with result 'exit-code'. 5月 16 16:08:18 ip-172-31-25-139.us-west-2.compute.internal systemd: Failed to start tomcat.service - Tomcat Server. I checked the directory /usr/share/tomcat9/bin and I did not see the file catalina.sh. Am I missing any steps in my installation?

I want to forward Microsoft Remote Desktop on a Linux Server, assume that the remote Windows host is 192.168.1.100, I want to run:

socat TCP4-LISTEN:3389,fork TCP4:192.168.1.100:3389
socat UDP4-LISTEN:3389,fork UDP4:192.168.1.100:3389

It works fine when I start the service by hand in the shell, but I want to start it with systemd, and log into /var/log/socat-rdp.log. After some trials I can run the service like this:

[Unit]
Description=Socat RDP Forwarding Service
After=network.target

[Service]
Type=forking
User=root
ExecStart=/bin/sh -c "/usr/bin/socat TCP4-LISTEN:3389,fork TCP4:192.168.3.153:3389 > /var/log/socat-rdp.log 2>&1 & /usr/bin/socat UDP4-LISTEN:3389,fork UDP4:192.168.3.153:3389 > /var/log/socat-rdp.log 2>&1 &"
ExecStop=/bin/kill $MAINPID

[Install]
WantedBy=multi-user.target

This configuration starts and runs normally, but when I stop the service with systemctl stop socat-rdp it returns error code 1, although socat process is killed as normal. Are there any better solutions?

I'm using Debian on WSL. Nix is already install. I install docker with this command: nix-env -iA nixpkgs.docker I want to start the daemon : systemctl start docker > Failed to connect to bus: No such file or directory **update** FYI $XDG_RUNTIME_DIR= /mnt/wslg/runtime-dir $UID=1000 $DBUS_SESSION_BUS_ADDRESS has no value ls -l /mnt/wslg/runtime-dir >drwx------ 4 pierre pierre 120 Dec 26 00:41 runtime-dir I can access the bus. But I need to use sudo sudo systemctl start docker Now I have this problem > Failed to start docker.service: Unit docker.service not found. I think docker.service is this file: /etc/systemd/system/docker.service But it doesn't exist on my OS. I'Ve tried to uninstall and reinstall docker with nix. To no avails I think that it is linked: https://discourse.nixos.org/t/docker-packages-systemd-unit-files-dont-work-on-ubuntu/12160 sudo cp ~/.nix-profile/etc/systemd/system/docker.service /etc/systemd/system/docker.service sudo cp ~/.nix-profile/etc/systemd/system/docker.sock /var/run/docker.sock sudo systemctl enable docker Failed to start docker.service: Unit docker.socket not found. >Failed to start docker.service: Unit docker.socket not found. After reading this link , I use this command in order to the know where I should replace docker.socket file. : systemctl list-sockets --all But no docker.socket is listed **update I have made all the commands from scratch. Now I have this problem A dependency job for docker.service failed. See 'journalctl -xe' for details.

In this context, an 'exception' is an undesirable scenario, which could be: a code-level signal (like SIGSEGV), incorrect ways of launching an app (like launching a command-line app as a daemon) etc. For a command-line app, the way to report exceptions to the user is by outputting to stderr - no doubts here. For a GUI app using GTK, an error window displayed using GTK's [MessageDialog](https://docs.gtk.org/gtk3/class.MessageDialog.html) can be used. But what if the MessageDialog fails, either due to unstable state of the app (SIGSEGV or SIGBUS may not have any recovery) or the API itself failed... in that case, how can a GUI app inform the user? Finally, a daemon... A daemon needs to inform user either due to a code-level exception (signals) or an external exception - user could launch a command-line app as a daemon, which is not a desirable way of launch, since a command-line app would've exited after its task is completed, but a daemon is expected to run for a long time. The command-line app could detect it was launched as a daemon and inform the user that it was launched incorrectly, but output to stderr does nothing here... how can a command-line app launched as daemon inform user that it was launched incorrectly? The main question is, how can each of these apps communicate with the user in the above mentioned scenarios? What is Linux's recommendation? PS: I'm new to Linux and app development in Linux.

I want my games and certain programs (such as WINE) to be automatically given a higher priority then everything else, and while I'm at it I probably want to adjust the niceness value of a few other things like my window manager to be given a higher priority as well. So is there any way to give a niceness level to a program before starting it? So, for example, I want the Steam program to always be run at niceness level -20 to give it priority over everything else. I don't want to have to run it in the command line like this "nice -n -20 steam" every time. A script could work well enough I suppose for those programs, but that doesn't solve it for things like services. For example, I might want to change the nice value of my window manager, which is started by my display manager, which is started by a service.

I just learning about daemon, by that time I came know avahi daemon can you please explain detaily about avahi daemon and why linux has a avahi user ?

I'm using Debian 6 and Dropbox. I followed [these commands](https://www.dropbox.com/install?os=lnx) to install it. When I run ~/.dropbox-dist/dropboxd — Dropbox works and stuff. Problem is that when I close terminal or, even worse — reboot, Dropbox stops working and I need to run that daemon again. How can I have the computer automatically start that daemon in the background?

I installed the following unit file for an Nodejs Express Server: [Unit] Description=Server for SpeedBot After=network.target [Service] ExecStart=/var/www/SpeedBot/server.js Restart=always User=nobody Group=nobody Environment=PATH=/usr/bin:/usr/local/bin Environment=NODE_ENV=production WorkingDirectory=/home/pi/SpeedBot/server.js [Install] WantedBy=multi-user.target When I run it and do: service speedbotserver status i get: ● speedbotserver.service - Server for SpeedBot Loaded: loaded (/etc/systemd/system/speedbotserver.service; disabled) Active: failed (Result: start-limit) since Thu 2017-06-29 01:31:18 UTC; 18h ago Process: 19189 ExecStart=/var/www/SpeedBot/server.js (code=exited, status=216/GROUP) Main PID: 19189 (code=exited, status=216/GROUP)

I am trying to get rtorrent to run as a systemd service, but the service wouldn't start. Here's the config file and any log I can get. Ask for more info if you need to. I am running:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.2 LTS
Release:        20.04
Codename:       focal

$ systemctl status rtorrent
● rtorrent.service - rTorrent
     Loaded: loaded (/etc/systemd/system/rtorrent.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Thu 2021-05-27 08:52:43 EEST; 5min ago
    Process: 20199 ExecStart=/usr/bin/tmux new-session -d -P -s rt -n rtorrent /usr/bin/rtorrent (code=exited, status=0/SUCCESS)
    Process: 20205 ExecStop=/usr/bin/tmux send-keys -t rt:rtorrent C-q (code=exited, status=1/FAILURE)
   Main PID: 20201 (code=exited, status=0/SUCCESS)

May 27 08:52:43 $MACHINE systemd[1] : Starting rTorrent...
May 27 08:52:43 $MACHINE tmux: rt:
May 27 08:52:43 $MACHINE systemd[1] : Started rTorrent.
May 27 08:52:43 $MACHINE tmux: no server running on /tmp/tmux-110/default
May 27 08:52:43 $MACHINE systemd[1] : rtorrent.service: Control process exited, code=exited, status=1/FAILURE
May 27 08:52:43 $MACHINE systemd[1] : rtorrent.service: Failed with result 'exit-code'.

The config file..

/etc/systemd/system/rtorrent.service 
[Unit]
Description=rTorrent
Requires=network.target local-fs.target

[Service]
Type=forking
KillMode=none
User=rt
Group=adm
ExecStart=/usr/bin/tmux new-session -d -P -s rt -n rtorrent /usr/bin/rtorrent
ExecStop=/usr/bin/tmux send-keys -t rt:rtorrent C-q
WorkingDirectory=/tmp/tmux-110/

[Install]
WantedBy=multi-user.target

Some more logs:

$ journalctl -u rtorrent
May 27 08:52:43 $MACHINE systemd[1] : Starting rTorrent...
May 27 08:52:43 $MACHINE tmux: rt:
May 27 08:52:43 $MACHINE systemd[1] : Started rTorrent.
May 27 08:52:43 $MACHINE tmux: no server running on /tmp/tmux-110/default
May 27 08:52:43 $MACHINE systemd[1] : rtorrent.service: Control process exited, code=exited, status=1/FAILURE
May 27 08:52:43 $MACHINE systemd[1] : rtorrent.service: Failed with result 'exit-code'.

So far I have added the user rt to the adm group, but I can't figure it out why tmux can't be started as rt. I also authorized rt user to launch services thanks to the enable-linger option: loginctl enable-linger rt I first added the rt user with:sudo adduser --system --gecos "rTorrent Client" --disabled-password --group --home /home/rt rt. How to make rtorrent run as systemd service with tmuxas a dedicated user? Or is there any other way to run it as service with systemd? Any help is really appreciated. **UPDATE:** So, just to get a fresh start, I have created a new user named rtorrent with: sudo adduser --system --gecos "rTorrent System Client" --disabled-password --group --home /home/rtorrent rtorrent and changed the /etc/systemd/system/rtorrent.service file to this (also adding system.daemon = true in /home/rtorrent/.rtorrent.rc, because of this post ):

[Unit]
Description=rTorrent System Daemon
After=network.target

[Service]
Type=simple
User=rtorrent
Group=rtorrent

ExecStartPre=-/bin/rm -f /home/rtorrent/.session/rtorrent.lock
ExecStart=/usr/bin/rtorrent -o import=/home/rtorrent/.rtorrent.rc
Restart=on-failure
RestartSec=3

[Install]
WantedBy=multi-user.target

But after all I get this error:

$ systemctl status rtorrent
● rtorrent.service - rTorrent System Daemon
     Loaded: loaded (/etc/systemd/system/rtorrent.service; enabled; vendor preset: enabled)
     Active: activating (auto-restart) (Result: exit-code) since Thu 2021-05-27 10:12:26 EEST; 2s ago
    Process: 22855 ExecStartPre=/bin/rm -f /home/rtorrent/.session/rtorrent.lock (code=exited, status=0/SUCCESS)
    Process: 22856 ExecStart=/usr/bin/rtorrent -o import=/home/rtorrent/.rtorrent.rc (code=exited, status=255/EXCEPTION)
   Main PID: 22856 (code=exited, status=255/EXCEPTION)

Why is this happening? What I am doing wrong? **UPDATE 2:** One more thing, This post suggest not dropping any files in the /etc/systemd/system/, but instead, to drop them in /usr/local/lib/systemd/system which in Debian based systems is in /lib/systemd/system. Therefore, I moved the unit-file there and when enabling it, it automatically created a symlink to /etc/systemd/system/. But still,, I get this error:

$ sudo systemctl status rtorrent
● rtorrent.service - rTorrent System Daemon
     Loaded: loaded (/lib/systemd/system/rtorrent.service; enabled; vendor preset: enabled)
     Active: activating (auto-restart) (Result: exit-code) since Thu 2021-05-27 10:39:14 EEST; 924ms ago
    Process: 24530 ExecStartPre=/bin/rm -f /home/rtorrent/.session/rtorrent.lock (code=exited, status=0/SUCCESS)
    Process: 24531 ExecStart=/usr/bin/rtorrent -o import=/home/rtorrent/.rtorrent.rc (code=exited, status=255/EXCEPTION)
   Main PID: 24531 (code=exited, status=255/EXCEPTION)

I have a service that stopped suddenly. I tried to restart that service but failed and was asked to run: systemctl daemon-reload. What does it exactly do? What is a daemon-reload?

I am trying to make a project written on Python work on a server. I created the following service file: [Unit] Description=My bot service After=multi-user.target [Service] Type=simple Restart=always ExecStart=/usr/bin/python3.10 /home/path/to/bot.py [Install] WantedBy=multi-user.target But this code doesn't work. If I check service status, it returns the following: ● test.service - My bot service Loaded: loaded (/etc/systemd/system/test.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Fri 2022-10-21 08:16:07 UTC; 15s ago Process: 156695 ExecStart=/usr/bin/python3.10 /home/path/to/bot.> Main PID: 156695 (code=exited, status=1/FAILURE) Oct 21 08:16:07 instance-1 systemd: test.service: Scheduled restart job, restart coun> Oct 21 08:16:07 instance-1 systemd: Stopped My bot service. Oct 21 08:16:07 instance-1 systemd: names.service: Start request repeated too quickly. Oct 21 08:16:07 instance-1 systemd: test.service: Failed with result 'exit-code'. Oct 21 08:16:07 instance-1 systemd: Failed to start My bot service. When I execute the bot directly (/usr/bin/python3.10 /home/path/to/bot.py), it works. When I run a simple Python script as a service, it also works. I just don't understand what can cause the problem inside the project. Adding WorkingDirectory parameter into the configurational file didn't change anything

I have an Ubuntu server with ~6-7 users. We all use some software that requires some shared files and folders to be regularly updated. Let's call that shared directory /opt/science/online-data Within this are some calibration and data files that are updated on an irregular basis on an external public server not owned by me. I have a cron job that runs an rsync command every day at 5 AM to keep it up-to-date. In everday usage, this folder just needs to be readable by all users (not written to). However, there are times where the software throws an error indicating that the online-data folder needs to be immediately updated before the software can be used. I'm not always around as admin to run that command. I'd like to set things up so that any of my users can run a script "update_online_data.py" or whatever, and it will trigger the rsync. I tried doing this by having the online-data folder group set to a specific group "softwaregroup" and giving all users membership, but the users are reporting permission errors. That's probably an error I can figure out (I'm pretty sure this should work.), but I wonder if there is a more secure way to do this anyway? Right now the group membership could in theory allow them to mess up those files when I really do not want them to do anything other than the rsync. Is there a way to create a command that triggers a non-login user specific to this task to do this and only this? (I have a vague idea that daemons or services might be a possibility, but I don't have a lot of experience using them in a custom way.)

I have a program that under normal activation listens on some port. I don't want the program running continuously. Is there a "quick and dirty" way to wrap the application in a shell script or similar that will monitor the appropriate port, and start the service on demand? The simplest approach would likely lead to the connection failing since the wrapper would have to let go of the port, and then start up the application. If the client simply connects again a short time later though, it could all work. But it would of course be even nicer if this was all completely transparent to the client.

I want to have a command run on my computer on startup, without me having to login. I want to do this because I want to have a program running all the time on my computer without me needing to login in the case that I restart my computer (instead of paying for a cloud computing service).

Looking at the following screen shot from System Monitor in Ubuntu 18.04.4 LTS (Linux 4.15.0-1079-oem), you see "(p-portal)" in the process list: I should have interrogated systemctl, ps and the like while it was up, but was busy on other things and mentally cataloged it for later follow-up. However, I cannot catch it up again! I cannot find it using DuckDuck, Bing or Google search. I thought it was perhaps associated with Chrome, which I had open at the time, but haven't seen it again with or without Chrome up. I had installed some Perl modules recently (Moo,Text-Template-1.61, Parallel-ForkManager-2.02), but didn't find it among the source files there. It doesn't appear in the output of systemctl list-unit-files at other times (as I said, I didn't check while it was visible in system monitor), nor output of pstree nor output from ps combined with xlsclients per the answer at https://unix.stackexchange.com/questions/175380/how-to-list-all-running-daemons I would appreciate hearing if anyone has encountered this process "p-portal" and knows what it is/does.

I have been using the sxhkd hotkey deamon together with bspwm. But unfortunately, sxhkd doesn' seem to be able to deal with the setup where the cntrl/super/alt keys are used as both modifiers and single keypress hotkeys: Hotkey 1: super (or Super_L) Hotkey 2: super + Return * When super is pressed-down, then return is pressed and released, hotkey 2 should fire, but hotkey 1 shouldn't * When super is pressed, and then released and no other key is pressed in the meantime, hotkey 1 should fire. Some people have suggested using xcape together with sxhkd, but this seems messy to me. Is there a hotkey deamon for linux that can just do this by itself, without requiring an extra tool like xcape?

I'm writing a daemon in C which needs to do some things as a separate user from root. I will call this user "testuser". My program is installed by its makefile. My question is thus, when should this user testuser be added? I could add it at the end of the install target:

install:
        something
        something
        useradd -r testuser

however if the user is already added (for example by a previous install) this will fail. -useradd -r testuser would surpress this error but this seems like bad practice. Also, another problem with doing it during make install would be if we are not actually installing the daemon for this system, e.g. make install DESTDIR=something. Should I leave the useradd to the system administrator and simply make the daemon fail with an error message if the user is not present? What are the conventions?

How do I find stdout of a process in openrc? Here's how I created my daemon. **/etc/init.d/mydaemon** #!/sbin/openrc-run command="python3" command_args="/srv/http/tornado.py" command_background="yes" pidfile="/tmp/tornado.pid" All I get in my logs is: * Starting tornado ... [ ok ] I have default /etc/rc.conf with set rc_logger="YES". What I would like to get is something like systemd allows to view stdout of a daemon with sudo journalctl -u mydaemon

I am setting up a service in /etc/init.d. I am looking at various scripts in there, some are implemented with start-stop-daemon ... and some with /path/to/script &. All of them save the pid in a file and do some checks. What is the best practice, what are the differences, what is important to know here ... ? (in general) In my particular case I have a simple lightweight localhost http server in java that an application will call once every hour or so and it just gives a stupid random number (no more details here, I just mean it doesn't use the file system or threads or anything complicated in case this matter in my question) Thanks

Unfortunately, due to hosting provider, I am unable to access the rsync daemon as root and secure it accordingly. Instead, in order to take regular remote backups from the server, I have to access the rsync daemon as a non-root user that has limited sudo privileges via the /etc/sudoers file. I have managed to get this to work and can successfully take backups, using the solution below (scroll down). **Additional Info Per Request** a.) non-root-username has this sudo privilege via /etc/sudoers: non-root-username ALL=NOPASSWD: /usr/bin/rsync b.) The goal is to use a non-root user to take secure remote backups of my system directory called /backups (using encrypted ssh connection and rysncd instead of rsync protocol to save on resources) c.) a single directory called /backups (which can successfully do with the solution below, I just want to make sure it is as secure as possible) **Question:** How do I make this non-root-user rsync daemon connection more secure? **Issues** Because sudo rsync does not save environment variables, I have a variety of issues: 1.) In the /etc/rsyncd.conf the hosts allow = function no longer works, server-side rsync.log, shows: rsync allowed access on module data from UNKNOWN (0.0.0.0) rsync on data/ from root@UNKNOWN (0.0.0.0) building file list 2.) Via /etc/ssh/sshd_config and/or /home/non-root-user/.ssh/authorized_keys I am unable to use ForceCommand, command=rsync --server --daemon ., respectively, for the actual rsync command. Any attempt to do so results in: rsync: did not see server greeting rsync error: error starting client-server protocol (code 5) at main.c(1675) [Receiver=3.1.3] 2a.) I currently have these values restricting my non-root-backup-user in my /etc/ssh/sshd_config... any additional recommendations? Match User non-root-username X11Forwarding no AllowTcpForwarding no PermitTTY no # ForceCommand /usr/bin/sudo /usr/bin/rsync <-- will not work # ForceCommand sudo rsync <-- will not work # ForceCommand rsync <-- will not work **My current solution:** Using: `rsync -a -e "ssh -l non-root-username" --rsync-path="sudo rsync" xx.xx.xx.xx::data /local/path` **Update:** The edit the above command caused @ERROR: auth failed on module data, therefore I had to change the auth user in the above /etc/rsyncd.conf to auth users: root and the same for /etc/rsyncd.conf root@admin:~# cat /etc/rsyncd.conf # Global configuration of the rsync service pid file = /var/run/rsyncd.pid #hosts allow = 123.123.123.123 <-- hashed out log file = /var/log/rsync.log # Username and group for working with backups uid = root gid = root # Don't allow to modify the source files read only = yes # Data source information [data] use chroot = false #strict modes = false <-- (defaults to true) path = /backups list = yes auth users = root secrets file = /etc/rsyncd.passwd In my /etc/rsyncd.passwd file, I have: root@admin:~# cat /etc/rsyncd.passwd root:password I have these permissions for /etc/rsyncd.conf: root@admin:~# stat /etc/rsyncd.conf File: /etc/rsyncd.conf Size: 471 Blocks: 8 IO Block: 4096 regular file Device: fd00h/64768d Inode: 144028 Links: 1 Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 1001/root) Access: 2022-05-21 13:38:46.797769245 +0800 Modify: 2022-05-21 13:38:42.641735637 +0800 Change: 2022-05-21 13:55:52.384894170 +0800 And, I have these permissions for /etc/rsyncd.passwd root@admin:~# stat /etc/rsyncd.passwd File: /etc/rsyncd.passwd Size: 31 Blocks: 8 IO Block: 4096 regular file Device: fd00h/64768d Inode: 144040 Links: 1 Access: (0640/-rwxrwxr-x) Uid: ( 0/ root) Gid: ( 1001/root) Access: 2022-05-21 13:38:06.989448597 +0800 Modify: 2022-05-21 13:37:37.473212811 +0800 Change: 2022-05-21 13:37:37.473212811 +0800 Any tips?