Is there any way to find out if the current session user is running an Xserver (under Linux) ?
I've started off with things like:
ps -e | grep X
but this doesn't work always
and one more thing I tried is checking the $DISPLAY variable
Are there any other ways to check this?
EDIT:
Some people suggested using the $DISPLAY variables but what if the user fiddles with this variable ? what if he tries to do something and changes this variable and then when I check it, it no longer reflects an accurate state of the system.
Is there no specific way to do this that will always return a correct answer ?
I found that it can be done programmatically thus:
#include <X11/Xlib.h>
int main()
{ exit(XOpenDisplay(NULL) ? 0 : 1); }
$ gcc -o xprobe xprobe.c -L/usr/X11R6/lib -lX11
But I am looking for a script way.
I often need to run an X command on a server that is running many X servers, so the ps based answers do not work. Naturally, $DISPLAY has to be set appropriately. To check that that is valid, use xset q in some fragment like:
if ! xset q &>/dev/null; then
echo "No X server at \$DISPLAY [$DISPLAY]" >&2
exit 1
fi
EDIT
Some people find that xset can pause for a annoying amount of time before deciding that $DISPLAY is not pointing at a valid X server (often when tcp/ip is the transport). The fix of course is to use timeout to keep the pause amenable, 1 second say.
if ! timeout 1s xset q &>/dev/null; then
⋮
$DISPLAY is the standard way. That's how users communicate with programs about which X server to use, if any.
One trick I use to tell if X is running is:
telnet 127.0.0.1 6000
If it connects, you have an X server running and its accepting inbound TCP connections (not usually the default these days)....
I use
pidof X && echo "yup X server is running"
pgrep and $DISPLAY are other options.
Other considerations:
su then $DISPLAY will not be set. Things that change the environment of the program running can make this not work.
I don't recommand ps -e | grep X as this will find procX, which is not the X server.
You can use xdpyinfo (can be installed via apt-get install x11-utils).
xprop -root &> /dev/null
...is my tried & true command to test for an "X-able" situation. And, it's pretty much guaranteed to be on any system running X, of course, the command fails if not found anyways, so even if it doesnt exist, you can pretty much assume there is no X either. (thats why I use &> instead of >)
I wrote xdpyprobe program which is intended for this purpose. Unlike xset, xdpyinfo and other general tools, it does not do any extra actions (just checks X server and exits) and it may not produce any output (if "-q" option is specified).
The bash script solution:
if ! xset q &>/dev/null; then
echo "No X server at \$DISPLAY [$DISPLAY]" >&2
exit 1
fi
Doesn't work if you login from another console (Ctrl+Alt+F?) or ssh. For me this solution works in my Archlinux:
#!/bin/sh
ps aux|grep -v grep|grep "/usr/lib/Xorg"
EXITSTATUS=$?
if [ $EXITSTATUS -eq 0 ]; then
echo "X server running"
exit 1
fi
You can change /usr/lib/Xorg for only Xorg or the proper command on your system.
1)
# netstat -lp|grep -i x
tcp 0 0 *:x11 *:* LISTEN 2937/X
tcp6 0 0 [::]:x11 [::]:* LISTEN 2937/X
Active UNIX domain sockets (only servers)
unix 2 [ ACC ] STREAM LISTENING 8940 2937/X #/tmp/.X11-unix/X0
unix 2 [ ACC ] STREAM LISTENING 8941 2937/X /tmp/.X11-unix/X0
#
2) nmap
# nmap localhost|grep -i x
6000/tcp open X11
#
First you need to ensure foundational X11 packages are correctly installed on your server:
rpm -qa | grep xorg-x11-xauth
If not then, kindly install all packages :
sudo yum install xorg-x11-xauth xterm
Ensure that openssh server is configured to forward x11 connections :
edit file : vim /etc/ssh/sshd_config
X11Forwarding yes
NOTE : If that line is preceded by a comment (#) or is set to no, update the file to match the above, and restart your ssh server daemon (be careful here — if you made an error you may lock yourself out of the server)
sudo /etc/init.d/sshd restart
Now, configure SSH application to forward X11 requests :
ssh -Y your_username#your_server.your_domain.com
if [[ $DISPLAY ]]; then
…
fi
This is PHP script for checking.
$xsession = `pidof X`;
if (!$xsession) {
echo "There is no active X session, aborting..\n";
exit;
}
Similar command can be used in shell script too. like the pidof command.
Related
I have a server where a certain port (9999) is being listened to by a PHP socket server. What happens is that devices can connect to the socket and send messages. The code works fine right now, however, I noticed that the socket would sometimes close or die off, and I need to be able to put it back up online automatically without me having to log in and run it again.
What I'm thinking of is writing a Shell script that would check via netstat if there's a process running on port 9999, and if there's none, the script would trigger the PHP socket server to go online again. This Shell script would then be called by Cron every 1 or 2 minutes to check if the PHP socket is running.
I have bare minimum knowledge about Shell scripting, and so far, this was the only other thing I wrote in Shell:
#!/bin/sh
if pidof "my process name here" >/dev/null; then
echo "Process already running"
else
echo "Process NOT running!"
sh /fasterthancron.sh
fi
I think I should be able to reuse this code to some degree but I'm not sure what to replace the if condition with.
I have the idea that I'm supposed to use netstat -tulpn to figure out what processes are running, but I'm not sure how to filter through that list to find if a specific process is running on port 9999.
If you use netstat -tlpn (or its replacement ss -tpln), you can grep for 9999 and look for processes listening on it under "Local Address".
ss -tpln | awk '{ print $4 }' | grep ':9999'
Alternatively, if you can, use netcat or telnet instead e.g. nc -v localhost 9999.
if echo -n "\cD" | telnet ${host} ${port} 2>/dev/null; then
...
fi
I wrote something similar a while back: docker-wait
This was forked from aanand's docker-wait
You can use famous netstat -tupln with a simple if/else logic to do this.
if [ -z "$(sudo netstat -tupln | grep 9999)" ];
then
echo notinuse;
else
echo inuse;
fi
I'm trying to get the list of processes running on my Windows machine from Linux, but I don't get any output when I do it in a script. If I use telnet manually and use the command pslist I get the complete list of processes, but not in my script.
Here is the bash script (minus the variables):
( echo open ${host}
sleep 1
echo ${user}
sleep 3
echo ${pass}
sleep 1
echo pslist
sleep 2
) | telnet
and I simply call it with bash pslist.sh and the output is something like that:
telnet> Trying ip_address...
Connected to ip_address.
Escape character is '^]'.
Welcome to Microsoft Telnet Service
login: my_loginmy_passwordpslistConnection closed by foreign host.
What am I doing wrong ?
telnet is notoriously tricky to script. You may be able to succeed more often if you add a longer still sleep between the commands.
A better approach is to switch to a properly scriptable client, viz. netcat (aka nc). Better still would be to install an SSH server on your Windows box (perhaps for security only make it accessible from inside your network) and set it up with passwordless authentication. Then you can simply ssh user#ipaddress pslist
Terminate each echo with \r character, like this: echo -e "${user}\r"
Sometimes TeamViewer disconnects itself (or gets disconnected) from its internet's main servers.
I am programming a script that will check if connection is lost and, if yes, kills and reopens the concerned process to make TeamViewer up and running again.
The problem is: I don't know how to discover that TeamViewer has lost its remote access capability (this is: the capability to be remotely accessed and controlled).
Tested until now:
Check TeamViewer process and/or daemon. Not valid: they keep working even after disconnected.
NICs review. Not valid: TeamViewer seems not to add any.
See the TeamViewer's main window. Not programmatically valid or easy to implement.
How can I programmatically know if TeamViewer has disconnected?
I don't know if this method differs between platforms, but at least I would like to know about a solution for some Linux shell. Bash if possible.
Probably I'm late, but run into the same problem and found a possible solution. I'm using teamviewer 12.
I noticed that, in my case sometimes some GUI related process are not launched so the machine is not online in my computer and contact list, if I ssh it and check for the list of teamviewer processes using:
ps -ef | grep [t]eamviewer
I get just one process, the teamviewer daemon:
root 1808 1 0 09:22 ? 00:00:53 /opt/teamviewer/tv_bin/teamviewerd -d
But, when everything is fine I have:
root 1808 1 0 09:22 ? 00:00:53 /opt/teamviewer/tv_bin/teamviewerd -d
rocco 10975 8713 0 09:31 ? 00:00:58 /opt/teamviewer/tv_bin/wine/bin/wineserver
rocco 11064 10859 0 09:31 ? 00:00:33 /opt/teamviewer//tv_bin/TVGuiSlave.64 31 1
rocco 11065 10859 0 09:31 ? 00:00:28 /opt/teamviewer//tv_bin/TVGuiDelegate 31 1
So simply counting the number of process works for me..
#!/bin/bash
online() {
## Test connection
ping -c1 www.google.com > /dev/null
return $?
}
online
if (test $? -eq 0)
then
network=$(ps -ef | grep [t]eamviewer | wc -l)
if (test $network -gt 3)
then
echo Machine online, teamviewer connected
else
echo Machine online, teamviewer not connected, trying restart daemon
sudo teamviewer --daemon restart
fi
fi
Have you considered trapping the signal(if possible) and executing a function that will restart TeamViewer.
Start it from a script and trap an exit signal
function restartTV {
# re-start TeamViewrt
sudo /etc/init.d/something start
}
trap finish EXIT # or appropriate signal
sudo /etc/init.d/something stop
# Do the work...
I have an instrument that streams data out a tcp port, and I'd like to use standard tools in a script to determine if the stream is available.
Manually I use ncat, which promptly exits if the data stream isn't available.
Here's my initial bash script:
#!/bin/bash
ncat somehost 1234 >/dev/null &
pid=$!
sleep 1
if [ -d /proc/$pid/ ]; then
kill -KILL $pid
echo "It's alive, ALIVE\!"
# Launch clients
else
echo "He's dead, Jim."
# Perform resurrection
fi
It works, but I'm wondering if there is a simpler or better way to accomplish this that doesn't rely on job control or procfs or even ncat. I'd also like to know how much data was sent before a timeout exires.
And, yes, in bash ncat host port can be replaced by cat </dev/tcp/host/port, but I'd also like to avoid bash-isms (so it can work under busybox).
Another approach would be to use wc to count the lines/chars output by ncat, since it outputs only one line and exits if the connection can't be made. But I can't wait forever for termination if the stream is up, so I'd need to use something like timeout, which has its own complications when trying to access the output of a command.
Is there a "plain" approach that works with minimal dependencies?
Or should I write a simple tool instead? It would return the number of bytes read if a connection was made to host/port, a negative errno otherwise, and would support a wait time and protocol spec (tcp/udp). A return value of 0 would mean the connection was made, but no data arrived before the wait time expired (a good thing to know).
Or maybe patch ncat to do the above?
I use netcat in FreeBSD, which has a -z option that simply checks whether a port is open. This eliminates the background and sleep you're using in your script.
-z Specifies that nc should just scan for listening daemons, without
sending any data to them.
The option exists in netcat on an old Ubuntu box here, so that might be an option for you.
$ nc -z somehost 1234 && echo "It's alive, ALIVE!"
I don't see an equivalent option in ncat. You may be able to compile netcat into busybox; it's much smaller than ncat, at least on my systems:
Linux:
$ ls -lH `which nc ncat`
-rwxr-xr-x 1 root root 31296 2010-02-21 01:32 /bin/nc
-rwxr-xr-x 1 root root 130448 2009-11-06 04:39 /usr/bin/ncat
FreeBSD:
ls -l `which nc ncat`
-r-xr-xr-x 1 root wheel 28112 Jan 15 14:53 /usr/bin/nc
-rwxr-xr-x 1 root wheel 182775 Mar 19 2012 /usr/local/bin/ncat
Of course, this doesn't help you check the amount of traffic that has come through the stream, or to analyse its content. For that, I think your solution is innovative and reasonable, though the challenge you've presented may not be resolvable easily.
You can use ps to avoid the procfs dependency, and you can store things in a temp file for analysis rather. Note that busybox should include a mktemp, but you should probably check the options. I haven't tested this:
#!/bin/sh
TMPFILE=`mktemp /tmp/str.XXXX`
trap "rm -f $TMPFILE" 0 1 2 3 15
nc somehost 1234 > $TMPFILE &
pid=$!
sleep 1
if ps $pid >/dev/null; then
kill -KILL $pid
echo -n "It's alive, "
if [ -s $TMPFILE ]; then
echo "ALIVE!"
else
echo "but unresponsive."
fi
else
echo "He's dead, Jim."
fi
That's all I've got. And it's not much different from what you already have.
Another option might be to build a custom tool that you might be able to compile into your own busybox, but that'll be a c question rather than a shell question. :-)
Per the title, I'm getting the following warning when I try to scp through an ssh tunnel. In my case, I cannot scp directly to foo because port 1234 on device foo is being forwarded to another machine bar on a private network (and bar is the machine that is giving me a tunnel to 192.168.1.23).
$ # -f and -N don't matter and are only to run this example in one terminal
$ ssh -f -N -p 1234 userA#foo -L3333:192.168.1.23:22
$ scp -P 3333 foo.py ubuntu#localhost:
ubuntu#localhost's password:
stty: standard input: Inappropriate ioctl for device
foo.py 100% 1829 1.8KB/s 00:00
Does anyone know why I might be getting this warning about Inappropriate ioctl for device?
I got the exact same problem when I included the following line on my ~/.bashrc:
stty -ixon
The purpose of this line was to allow the use of Ctrl-s in reverse search of bash.
This gmane link has a solution: (original link dead) => Web Archive version of gmane link
'stty' applies to ttys, which you have for interactive login sessions.
.kshrc is executed for all sessions, including ones where stdin isn't
a tty. The solution, other than moving it to your .profile, is to
make execution conditional on it being an interactive shell.
There are several ways to check for interecative shell. The following solves the problem for bash:
[[ $- == *i* ]] && stty -ixon
Got the same issue while executing the script remotely. After many tries didn't get any luck to solve this error. Then got an article to run a shell script through ssh. This was an issue related to ssh, not any other command. ssh -t "command" -t will allocate a pseudo TTY to the ssh and this error won't come.
at the end i created a blank .cshrc file ( for ubuntu 18.04). worked