Questions tagged [signal]

Questions about signals, a kind of interprocess communication.

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What is the correct way to see what signals a process handles?

EDIT: Since my question was not clear let me reformulate: how can one find what signals a process handles? From this answer: https://unix.stackexchange.com/questions/85364/how-can-i-check-what-signals-...
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1answer
28 views

Postgresql service stopping on its own in ubuntu server

In the postgresql log file, I found message: startup process (PID 1886772) was terminated by signal 9: Killed Although upon restarting service, postgresql database starts functioning normally. ...
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On attempt to install Signal, I think I made some mistake and now getting some error in Ubuntu 20.04 LTS. How to correct this? Thank you [duplicate]

On sudo apt update command I get the following output: > sudo apt update [sudo] password for chess: Hit:1 http://ppa.launchpad.net/alexlarsson/flatpak/ubuntu focal InRelease Hit:2 https://...
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74 views

Notification when some input (stdin, file, named pipe) is available? [closed]

is there some mechanism to be notified asynchronously when input from a 'file' is available? I have a program that cyclically does its work. So far so good. But there also is a serial line and ...
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1answer
225 views

Input signal out of range Change settings to 1600x900 60 [duplicate]

Ubuntu was working fine till i changed the resolution to one that was higher than the recommended settings(1600x900) now i don't know what to do. Any help?
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1answer
412 views

Make gnome-terminal request user confirmation before close

When you open gnome-terminal without any options and execute a blocking command (e.g. python3, vim or cat) and then try to close the window by the close button (i.e. x button in the title bar) or some ...
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1answer
11k views

Why does Ctrl + C not kill Python running in terminal?

I am trying to understand the reason why the whole Python process does not get killed when I press Ctrl + C inside and infinite loop or for that matter any Python function that I am running in ...
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1answer
599 views

HDMI monitor not receiving signal after waking up from suspend mode

i have a problem that after I wake my ubuntu 18.04 laptop from the suspend mode, my HDMI monitor, which is set up a the primary monitor in the extended display set up, is not receiving the signal. I ...
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3answers
579 views

Is there any conflict between nohup and mpirun?

I want to start a big simulation on an ubuntu desktop computer. I have physical (not remote) access to this PC. This simulation may take some weeks. The command to start the process is: mpirun -np ...
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0answers
104 views

half signal strength from wireless rtl8188ce lubuntu

I get super slow speeds (half the signal strength I get on windows) and an unstable connection. I ran this script and this is the info I get on Lubuntu 19.04 Kernel 5.0.0-29-generic. 02:00.0 Network ...
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278 views

How to move one process from SWAP to RAM?

As far as I can see, there is a design error in how my processes are moved between SWAP and RAM: If RAM gets full, some are moved to SWAP. So far so good. But if RAM gets freed, they are not moved ...
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1answer
46 views

What does it mean when ^\ doesn't work, but kill -9 does?

Recently, I've had a third-party program hang in a weird way. It stops taking input or output, and ^C and ^\ do nothing. kill -9 and killing the parent process do end it. What state could the process ...
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1answer
112 views

SIGQUIT breaks the pipe

Linux ping utility can produce some statistics on receiving SIGQUIT without terminating. It looks like this: PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_seq=1 ttl=45 time=...
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1answer
813 views

Synchronize Signal contacts on signal-desktop in Ubuntu 18 from Signal on Ubuntu Touch (Fairphone2)

I installed the Signal app on my Fairphone2 running Ubuntu Touch. Contacts were correctly imported from contacts list to the app. I installed the Signal desktop client for Ubuntu 18 on my computer ...
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19 views

Difference in Wifi connection %'s?

This is something I've wondered about for a long time...Ubuntu 16.04 using Cinnamon. On a tower computer. In the action bar I have the Wifi icon. It shows that I'm currently connected to the local ...
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0answers
43 views

Which version of Signal Desktop is legit? [duplicate]

I saw both of these in the apt sources. Since this is a secure communications app, what is the correct source to use for Ubuntu? Searching for Signal, I see: And lower: With these details: Before ...
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0answers
341 views

Multiple repository errors when I try any APT command after trying to install signal [duplicate]

I am currently using 18.04. I wanted to install signal for desktop and I got this code from the site to install on Debian: curl -s https://updates.signal.org/desktop/apt/keys.asc | sudo apt-key add ...
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1answer
727 views

Send multiple kill signals to a process

Say I run a .sh process. And now I open a new terminal tab and I want to send signals to it, for that, I just use kill: kill -*signal number* *pid* right? But I want to send 13 signals at the same ...
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1answer
684 views

Signal messenger app not starting up

Over the past 2 weeks (after installing Ubuntu 18.04 from scratch) I have had problems on and off with the Signal messenger app. It sometimes doesn't start up at all. Uninstalling and reinstalling ...
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2answers
802 views

Sending SIGSTOP or SIGCONT signals graphically (similar to xkill)

Question Do you know any tool/script to send SIGSTOP (to pause a process) or SIGCONT (to resume it) to a process by clicking on a graphical window generated by the process? Some context There is ...
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1answer
551 views

Week wireless signal in Linux mint [closed]

After installing Linux Mint 18.3 "Sylvia" - Cinnamon (64-bit) on my HP laptop, I realize that the WiFi signal is a way too weak and the modem and the router is near my laptop. Model: HP Probook 4540s
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How can I get yarn to use the right version of Node?

I am new to Node, JavaScript etc. and want to try messing with the code of Signal. For this I need a specific version of Node. I did this (on Ubuntu 16.04) using the following procedure: wget https://...
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370 views

Upstart service killed by TERM signal, how to track that

I have upstart script as description "My API API" author "me@localhost" env MY_API_PYTHON_HOME=/opt/services start on runlevel [2345] stop on runlevel [!2345] script mkfifo /tmp/my-api-log-fifo ...
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1answer
3k views

Ubuntu 16.04, hdmi monitor: no signal in login screen

My main monitor is connected over HDMI and my second one over DVI. Both get a signal when the PC starts up, but the moment I get to the login screen the HDMI one goes dark, though it doesn't seem to ...
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1answer
209 views

Chromium Signal App crashing in Xubuntu

When I try to launch Signal through the launcher on Linux with the following /usr/bin/chromium-browser --profile-directory=Default --app-id=bikioccmkafdpakkkcpdbppfkghcmihk It crashes, nothing ...
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0answers
124 views

Ubuntu 16.04LTS Four monitor display issue

I've been browsing the forum trying to find a solution to my specific problem but can't find anything specific. My graphics card is the Radeon R9 380 Sapphire Nitro. I have three DVI displays, one of ...
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1answer
146 views

Why sigset includes unadded SIGINT? [closed]

Wrote simple program to learn writing POSIX style signal handling. #include <signal.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> static void sig_int(int); ...
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1answer
275 views

Disable “System program problem detected” for segfaults in my own programs

I don't mind being notified about system programs that SEGV -- I would actually like to report those cases, so this is not a duplicate of Getting “System program problem detected” pops up regularly ...
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1answer
2k views

Weak WiFi signal in Ubuntu on HP G240 G5 [duplicate]

I had purchased new HP 240 G5 laptop. Wifi is working good with windows but in ubuntu 16 wifi signal comes very weak. Below are laptop wifi details, *-network description: Wireless interface ...
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0answers
76 views

Ubuntu 16.04 immediately terminates all running programs on restart or shutdown?

When I choose restart or shutdown in Ubuntu 16.04, it immediately terminates all running applications. I'm not prompted to save open documents or anything like that - and I've lost work several times ...
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2answers
499 views

How to pass SIGALRM to a program which finishes execution in milliseconds?

I have a C program which computes the first n prime numbers if n is passed as an argument. $ ./prime 5 2 3 5 7 11 The logic of the program allows me to enter into a desired function if I can give ...
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1answer
3k views

No SIGTERM before SIGKILL/shutdown with systemd on Ubuntu 16.04

I ran across this problem while I tried to answer a question on Stackoverflow. On shutdown, Ubuntu 12.04 sends SIGTERM to all processes and waits at most 10 seconds before killing them with SIGKILL (...
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1answer
617 views

After upgrade to 16.04, wifi signal strength jumps from perfect to zero and back

I upgraded from 14.04 LTS to 16.04 LTS on HP Z230. Internet connection worked perfectly under 14.04 LTS. There were no hardware changes. The computer connects to the router by a wireless usb device (...
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1answer
788 views

xvfb-run hangs on trap/wait in Elastic Bamboo's Ubuntu 15.04 AMI on AWS

I'm trying to run some headless robot/Selenium tests via Elastic Bamboo using Xvfb, on Ubuntu 15.04 in AWS EC2. It works if I run Xvfb manually and then run the test... export display=:99 Xvfb :99 -...
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2answers
432 views

Ubuntu 14.04 wireless unstable and the signal is weak

I installed Ubuntu 14.04 LTS alongside Win8.1 and the wireless was unstable. I updated windows network drivers then it went better but the signal is still very weak and also sometimes network switches ...
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2answers
2k views

Wifi apparently connected, but webpages won't load

I'm running the latest Ubuntu 14.04.3, and my issue today is that my Wifi connection sometimes becomes really slow, and eventually disconnects. I tried googling around to see if I can get any good ...
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2answers
950 views

Difference between C programs and shell scripts receiving signals from fuser

I have written the shell script below for a lab in my college. It must look at a log file being upgraded frequently from another process and create a number of copies passed at invokation. Here is the ...
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1answer
2k views

index out of range? [closed]

# load parameters file yml = yaml.load(open(sys.argv[1])) # imports for pkg, functions in yml['imports'].iteritems(): stri = 'from ' + pkg + ' import ' + ','.join(functions) exec(stri) ...
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0answers
425 views

Why does sudo prevent catching SIGTSTP (Ctrl+Z)?

This program is written to catch SIGTSTP (Ctrl+Z) and bypass its normal effect, printing a message and returning to its normal operation instead of allowing its process to be suspended: #include<...
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0answers
70 views

The UBUNTU Graphics Catch 22

Trying to use a Live DVD to run Ubuntu 14.04.1, I get the "Monitor signal out of range" error. I hit ctrl-alt-F1 to bring up the command line. I do sudo nano /etc/default/grub and remove # from ...
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2answers
1k views

12.04 wifi signal very weak

Ii am new people in Ubuntu I am using 12.04 version , but my wifi signal very weak My router beside me only , my signal also only 50% ... Anybody know how to fix it?i have try to research solution, ...
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1answer
3k views

emit signal with custom type objects array parameter from c++ and receive in qml

I would like to emit a signal from a Qt C++ class which includes a parameter that is an array of custom objects (inherited from QObject) and receive the parameter in its qml slot, but i'm afraid it is ...
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1answer
63 views

sigfillset is not setting signal bits

I am having this strange problem! My code is very simple. #include<stdio.h> #include<unistd.h> #include<signal.h> #include<stdlib.h> main(...
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1answer
2k views

What do these Terminal Signals mean?

When I start to use a command to terminate an ongoing process, I can include a signal. What is the difference between the signal 9 and the signal 15?
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1answer
238 views

Ubuntu 13.10, not recognizing 2nd monitor

Just installed ubuntu for the first time and my monitor isn't showing up on the display settings. I am on a laptop with nivdia graphics if that helps. I believe I have bumblebee installed. Other ...
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0answers
346 views

Core only dumped upon receiving SIGQUIT

Learning about signals, I found out that calling the <stdlib.h> functionabort(void); in a C program, which roughly equals to raising a SIGABRT signal, doesn't create a core file on my Ubuntu 13....
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0answers
1k views

Unix Signal handling in Qt Embedded Linux [closed]

I have an application for the USB interface in Qt (Embedded Linux). When a pen-drive is inserted, the kernel sends a signal for that and I want to recognize that signal and I want my Qt application ...
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1answer
979 views

TP Link TL-WN7200ND Signal Strength

I have external Wireless Adapter TP Link TL-WN7200ND I'm currently using it on Windows its giving me 4/5 signal bars When I used same Adapter in Ubuntu 13.04 it gives 2/4 bars. I'm using Live USB for ...
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0answers
443 views

no internet connection, but have signal in wifi

I cannot access yahoo.com, google etc in my browser, but I have signal in my WiFi, how can I access the internet again? Please can you tell me how to configure and solve my problem, Thanks
3
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1answer
2k views

Bad WiFi reception on Asus Zenbook (Works great with Windows 7)

My WiFi reception on my Asus Zenbook (model ux31) is very weak compared to when I boot my Windows 7. I use both from the same location, and the reception on other devices (ex: my iPhone) is great. I'm ...