Following script I use to start vnc,
cd $HOME; vncserver -kill :12
cd $HOME; vncserver :12 -geometry 1280x1024 -name myvnc --alwaysshared
It works when I run from terminal, but It gives error when run from cronjob
Screenshot of vnc when start from cron
Machine configuration
Operating System: Red Hat Enterprise Linux Server 7.6 (Maipo)
CPE OS Name: cpe:/o:redhat:enterprise_linux:7.6:GA:server
Kernel: Linux 3.10.0-957.el7.x86_64
Architecture: x86-64
Machine was up for last 141 days, after reboot of machine the above issue gets resolved. Can any one tell me how to figure out what cause this issue to arise?
Update:
Still, issues arise within every 3-4 days after reboot.
Suspects are as follows:
cron job user has been changed to/from root, and so $HOME has changed accordingly.
Try an "&& wait" to make sure the -kill has finished before issuing the next command.
Do you have a MAX sessions set? Has it been reached? And X may be the issue.
Curious, what is the system response when you do the following? Is the previous session still running? Did the -kill command complete? Does it always?
vncserver -kill :12
ps -fU "$USER" | grep vnc # or try: ps -e | grep vnc
May I suggest the following to aid the debug process...
#!/bin/sh
cd "$HOME" || exit 1 # a good habit, don't assume the landing.
echo "$HOME" # confirm that the value is what you expect.
vncserver -kill :12 && wait # wait for the kill to complete before restarting
vncserver :12 -geometry 1289x1024 -name myvnc --alwaysshared
exit 0
Perhaps even better:
#!/bin/sh
cd "$HOME" || exit 1
if ! vncserver -kill :12 ; then
vncserver :12 -geometry 1289x1024 -name myvnc --alwaysshared
else
echo "Error: vncserver 12 Process NOT KILLED, $? " # $? will give you the return/exit value of previous
fi
exit 0
Notes:
You didn't say what shell you are using but you can substitute #!/bin/bash in place of #!/bin/sh
You didn't paste the error statement.
Find a hack,
If I create vnc from root user then it works perfectly.
In cron you can add entry as below
su - myuser -c "cd $HOME; vncserver -kill :12; vncserver :12 -geometry 1280x1024 -name myvnc --alwaysshared "
Related
I use Ubuntu 14.04.4 LTS and installed vnc4server.
The basic script starting vncdesktops is under /etc/init.d/vncserver which is a bash script. This works fine for all users specified in /etc/vncserver/vncservers.conf with their arguments. But when a user is using csh instead of bash, the vncserver command doesn't work because of a syntax error in the vncserver script. The error occurs in the start() function which I show here.
start() {
. /lib/lsb/init-functions
REQ_USER=$2
echo -n $"Starting $prog: "
ulimit -S -c 0 >/dev/null 2>&1
RETVAL=0
for display in ${VNCSERVERS}
do
export USER="${display##*:}"
if test -z "${REQ_USER}" -o "${REQ_USER}" == ${USER} ; then
echo -n "${display} "
unset BASH_ENV ENV
DISP="${display%%:*}"
export VNCUSERARGS="${VNCSERVERARGS[${DISP}]}"
su ${USER} -c "cd ~${USER} && [ -f .vnc/passwd ] && vncserver :${DISP} ${VNCUSERARGS}"
fi
done
}
When I give the command 'sudo service vncserver restart' the vncserver script runs and give me this error for a user using csh.
Starting VNC server: 8:test1 [: No match.
user 'test1' is using csh and its display number is 8. I can see this error is coming from the line
su ${USER} -c "cd ~${USER} && [ -f .vnc/passwd ] && vncserver :${DISP} ${VNCUSERARGS}"
and I understand what it's doing but I don't know why the bracket condition is giving me this error and that only for a user using csh.
Can anyone give me a clue?
I don't know exactly why, but I found my /bin/csh was linked as below.
/bin/csh -> /etc/alternatives/csh
So I installed tcsh (apt-get install tcsh) and made the link like this.
/bin/csh -> /bin/tcsh
Then the problem is gone!
The su command and the command executed by -c option is being processed in the su'ed user's shell which was /etc/alternatives/csh which probably could not handle the [ -f ] condition. and I gues the /etc/alternatives/csh is a kind of default csh linked to when there is no real full fledged csh(like tcsh).
I have a script in cron to check memcached and restart it if it's not working. For some reason it's not functioning.
Script, with permissions:
-rwxr-xr-x 1 root root 151 Aug 28 22:43 check_memcached.sh
Crontab entry:
*/5 * * * * /home/mysite/www/check_memcached.sh 1> /dev/null 2> /dev/null
Script contents:
#!/bin/sh
ps -eaf | grep 11211 | grep memcached
if [ $? -ne 0 ]; then
service memcached restart
else
echo "eq 0 - memcache running - do nothing"
fi
It works fine if I run it from the command line but last night memcached crashed and it was not restarted from cron. I can see cron is running it every 5 minutes.
What am I doing wrong?
Do I need to use the following instead of service memcached restart?
/etc/init.d/memcached restart
I have another script that checks to make sure my lighttpd instance is running and it works fine. It works a little differently to verify it's running but is using the init.d call to restart things.
Edit - Resolution: Using /etc/init.d/memcached restart solved this problem.
What usually causes crontab problems is command paths. In the command line, the paths to commands are already there, but in cron they're often not. If this is your issue, you can solve it by adding the following line into the top of your crontab:
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
This will give cron explicit paths to look through to find the commands your script runs.
Also, your shebang in your script is wrong. It needs to be:
#!/bin/bash
I suspect the problem is with the grep 11211 - it's not clear the meaning of the number, and that grep may not be matching the desired process.
I think you need to log the actions of this script - then you see what's actually happening.
#!/bin/bash
exec >> /tmp/cronjob.log 2>&1
set -xv
cat2 () { tee -a /dev/stderr; }
ps -ef | cat2 | grep 11211 | grep memcached
if [ $? -ne 0 ]; then
service memcached restart
else
echo "eq 0 - memcache running - do nothing"
fi
exit 0
The set -xv output is captured to a log file in /tmp. The cat2 will copy the stdin to the log file, so you can see what grep is acting upon.
Save below code as check_memcached.sh
#!/bin/bash
MEMCACHED_STATUS=`systemctl is-active memcached.service`
if [[ ${MEMCACHED_STATUS} == 'active' ]]; then
echo " Service running.... so exiting "
exit 1
else
service memcached restart
fi
And you can schedule it as cron.
I'm trying to run a script in a tmux environment on another computer using ssh, but the ssh connection won't terminate until the script has finished. Let me explain this in detail:
This is test_ssh.sh:
#!/bin/bash
name="computername"
ssh $name /bin/bash <<\EOF
cd /scratch
mkdir test
cd test
cp /home/user/test_tmux3.sh .
tmux -c ./test_tmux3.sh &
echo 1 # at this point it waits until test_tmux3.sh is finished, instead of exiting :(
EOF
This is test_tmux3.sh (as a test to see if anything happens):
#!/bin/bash
mkdir 0min
sleep 60
mkdir 1min
sleep 60
mkdir 2min
At the end I would like to loop over multiple computers ($name) to start a script on each of them. The problem I am having right now is that test_ssh.sh waits after the echo 1 and only exits after tmux -c test_tmux3.sh & is finished (after 2 minutes). If I manually enter control-C test_ssh.sh stops and tmux -c test_tmux3.sh & continues running on the computer $name (which is what I want). How can automate that last step and get ssh to exit on its own?
Start the command in a detached tmux session.
#!/bin/bash
name="computername"
ssh $name /bin/bash <<\EOF
mkdir /scratch/test
cd /scratch/test
cp /home/user/test_tmux3.sh .
tmux new-session -d ./test_tmux3.sh
echo 1
EOF
Now, the tmux command will exit as soon as the new session is created and the script is started in that session.
Have you tried to use nohup command to tell to the process keep running after exit?:
#!/bin/bash
name="computername"
ssh $name /bin/bash <<\EOF
cd /scratch
mkdir test
cd test
cp /home/user/test_tmux3.sh .
nohup tmux -c ./test_tmux3.sh &
echo 1 # at this point it waits until test_tmux3.sh is finished, instead of exiting :(
EOF
I have this script:
#!/bin/sh
while [ true ] ; do
urlfile=$( ls /root/wget/wget-download-link.txt | head -n 1 )
dir=$( cat /root/wget/wget-dir.txt )
if [ "$urlfile" = "" ] ; then
sleep 30
continue
fi
url=$( head -n 1 $urlfile )
if [ "$url" = "" ] ; then
mv $urlfile $urlfile.invalid
continue
fi
mv $urlfile $urlfile.busy
wget -b $url -P $dir -o /www/wget.log -c -t 100 -nc
mv $urlfile.busy $urlfile.done
done
The script basically checks for any new URLs at wget-download-link.txt for every 30 seconds and if there's a new URL it'll download it with wget, the problem is that when I try to run this script on Putty like this
/root/wget/wget_download.sh --daemon
it's still running in the foreground, I still can see the terminal output. How do I make it run in the background ?
In OpenWRT there is neither nohup nor screen available by default, so a solution with only builtin commands would be to start a subshell with brackets and put that one in the background with &:
(/root/wget/wget_download.sh >/dev/null 2>&1 )&
you can test this structure easily on your desktop for example with
(notify-send one && sleep 15 && notify-send two)&
... and then close your console before those 15 seconds are over, you will see the commands in the brackets continue execution after closing the console.
The following command will also work:
((/root/wget/wget_download.sh)&)&
This way you don't have to install the 'nohub' command in the tight memory space of the router used for OpenWrt.
I found this somewhere several years ago. It works.
The &at the end of script should be enough, if you see output from the script it means, that stdout and/or stderr is not closed, or not redirect to /dev/null
You can use this answer:
How to redirect all output to /dev/null
I am using openwrt merlin and the only way to get it working was using the crud cron manager[1]. Nohub and screen are not available as solutions.
cru a pinggw "0 * * * * /bin/ping -c 10 -q 192.168.2.254"
works like charm
[1][https://www.cyberciti.biz/faq/how-to-add-cron-job-on-asuswrt-merlin-wifi-router/]
https://openwrt.org/packages/pkgdata/coreutils-nohup
opkg update
opkg install coreutils-nohup
nohup yourscript.sh &
You can use nohup.
nohup yourscript.sh
or
nohup yourscript.sh &
Your script will keep running even if you close your putty session, and all the output will be written to a text file in same directory.
nohup is often used in combination with the nice command to run processes on a lower priority.
nohup nice yourscript.sh &
See: http://en.wikipedia.org/wiki/Nohup
For busybox in Openwrt Merlin system, I got a better solution which combined cru and date command
cru a YOUR_UNIQUE_CRON_NAME "`date -D '%s' +'%M %H %d %m *' -d $(( \`date +%s\`+2*60 ))` YOUR_CMD_HERE"
which add a cron job running 2 minutes later, and only run once.
Inspired by PlagTag's idea.
In another way these code would tried:
ssh admin#192.168.1.1 "/jffs/your_script.sh &"
Simple and without any programs like nohup screen...
(BTW: worked on Asus-Merlin firmware)
Try this:
nohup /root/wget/wget_download.sh >/dev/null 2>&1 &
It will go to the background so when you close your Putty session, it will be still running, and it won't send messages to the terminal.
Alright, so I have a .sh file that I run that will launch my server with the certain specifics that I'm looking for. It launches the server through screen into it's own screen. Here's the code for my run.sh file.
#!/bin/bash
# run.sh
# conversion of run.bat to shell script.
echo "Protecting srcds from random crashes"
echo "Now launching Garrys Mod RequiemRP"
sleep 5
screen -A -m -d -S gmserver ./srcds_run -console -game garrysmod +maxplayers 32 +map rp_downtown_v6 -autoupdate
echo "Server initialized. Type screen -x to resume"
Usually I use a batch file to do this, but I'm now using linux for my server hosting. Part of that batch file was if srcds (the server itself) were to crash, the run.bat file would restart the server automatically. I'm looking to do this with my run.sh file, but I'm unsure how to.
Perhaps you could make a service or script that will periodically check if the process is running. This will check if it's on and if it isn't, it will turn it on when executed.
#!/bin/bash
ps cax | grep srcds > /dev/null
if [ $? -eq 0 ]; then
exit
else
bash /path/to/run.sh
fi
I tested the command and it works. For my virtualized debian 9 system.