I created a c++ programm that works with ros. The first step would be to open a roscore in a terminal and move on from there. I do so with system("roscore &");
I compiled my file and can run it just fine with ./file.
However, I want to be able to run it as an application (double click). I created a .desktop file and the program shows up in my application list. When i start it though, all I get is a terminal that opens with the message
sh: 1: roscore: not found
etc.
The same applies for the roslaunch commands. I also fork and exec a roslaunch command, which does not work as well.
I tried system("ls"); which worked. All cout messages work as well.
Any idea what is wrong here?
roscore executable is not located in std paths (/bin:/usr/bin:). Use the absolute path - system("/path/to/roscore &")
I'm making a basic music player in C++ on an embedded Linux platform (Intel Edison).
It works by sending commands to the shell to play the music using mpg123.
Playing the music is working fine, but now I need to add media controls. I'm using the mpg123 command to play my MP3 files and if you pass it the -C flag then it listens for commands such as p for pause, q for quit, etc
I'm using the code from this other SO answer for executing the commands How to execute a command and get output of command within C++ using POSIX?
Now the thing is, when I run the command to play the selected song from c++ (eg. mpg123 -C /media/sdcard/Music/<songname>) it hangs the c++ program until the command returns, which doesn't return until the song is done playing. I can eliminate that issue by using pthead to run the command in a parallel thread, but that still doesn't allow me to enter commands as I need to.
I thought of maybe somehow running the command in another tty, and then somehow passing the commands to mpg123 by sending them to the other tty, but I was unable to find a way to do this. (and I'm not sure it's possable)
I've been trying to do this for hours, so now I'm ready to ask here for some help :)
Do any of you have any ideas on how to run the command without freezing the thread (in a pthread or whatever), and still be able to send commands to mpg123?
It sounds like you'll want to use mpg123's FIFO mode. You set a pathname to be used, point mpg123 at it and then echo your commands into it.
This answer has a great example
FIFO_MPG='/srv/http/newsctl'
mpg123 -R --fifo "$FIFO_MPG"
echo 'load filename.mp3' >> "$FIFO_MPG"
I am writing a program that logs into another system via SSH using the libssh2 library. Once logged in, I execute a command using:
libssh2_channel_exec(sshchannel, command)
The command executes okay. However, once I close the channel the process running is killed. In my case, the command (executing a binary executable) will run for a long period of time and my program cannot wait for it to terminate. I've tried issuing the following commands all to the same result (the process is still killed upon closing the channel):
/path/myprog
nohup /path/myprog
nohup /path/myprog &
/path/myprog &; disown
Further, I've observed this behavior for both libssh and libssh2. Is there some option or command I am missing?
Thanks in advance.
you can use the unix at command:
echo "cmd" | at now
I recently reinstalled Cygwin on my computer in order to get access to several command line elements that I was missing. I have never had previous difficulty with Cygwin, but after this reinstallation, an error message continues to appear after (almost) each command entered. For instance:
-bash-4.1$ wc m1.txt
3 [main] bash 2216 child_info_fork::abort: data segment start: parent(0x26D000) != child(0x38D000)
-bash: fork: retry: Resource temporarily unavailable
2013930 4027950 74968256 m1.txt
Generally, the command still runs (as seen above), but not always. Occasionally, the 'error' message occurs several times in a row (the initial number "3" will then change to a "4" or "2", notably if I start a second Cygwin window.
Also, as soon as I start up Cygwin, I get the following message before the prompt:
3 [main] bash 6140 child_info_fork::abort: data segment start: parent(0x26D000) != child(0x36D000)
-bash: fork: retry: Resource temporarily unavailable
-bash: fork: Resource temporarily unavailable
-bash-4.1$
At the moment, I am debating whether to uninstall/reinstall Cygwin again or just live with the error messages, but I was curious if there might be an issue that I am unaware of.
(assuming Cygwin is installed at C:\Cygwin):
Open Task Manager and close any processes that look to be Cygwin related.
Open C:\Cygwin\bin in Windows Explorer
Verify that dash.exe, ash.exe, rebase.exe, and rebaseall exist in this folder
If any of them are missing, re-run Cygwin setup and select the dash, ash, and rebase packages
right-click your C:\Cygwin folder, uncheck Read-only (if its checked), and press OK.
When an error about not being able to switch some files comes up, select "Ignore All". Wait for this process to complete.
Browse to C:\Cygwin\bin in Windows Explorer
Right click dash.exe and click "Run as Administrator". A command Prompt should appear with nothing but a $
Type /usr/bin/rebaseall -v, hit enter, and wait for the process to complete.
If you get errors about Cygwin processes running, try Step 1 again. If that still doesn't work, Restart your computer into safe mode and try these steps again.
A commenter noted that, depending on your settings, you may have to type cd /usr/bin && ./rebaseall -v instead.
Try opening Cygwin again.
This process worked for me. I hope it works for you guys too.
Source: http://cygwin.wikia.com/wiki/Rebaseall
I would like to add the following to the above answers, as it is what I had to do after reinstalling Cygwin:
Navigate to the "/usr/bin" directory (usually, C:\cygwin\bin) and right click, Run as Administrator the file: dash.exe
Then, at the $ prompt type the following, hitting enter after each line:
cd /usr/bin/
/usr/bin/peflags * -d 1
/usr/bin/rebaseall -v
What it does is, it marks the dll's as "rebase-able," and then rebases them. You have to have peflags.exe in addition to the above files (in previous answers). You may have to restart windows after doing this and you will definitely need to make sure that there are no processes nor services belonging to cygwin running. (Use task manager, kill any related processes, and then under the services tab look for any service starting with CYG and stop it.)
After doing this, I was able to get cygwin to run without any errors about dll's being loaded to the wrong addresses aka fork errors, etc.
I hope that this helps others, as it was a pain to find.
SOURCE: http://www.cygwin.com/faq.html#faq.using.fixing-fork-failures
and the rebase README file.
To add on to other answers here, we ran into the same issue but could not run the rebase command from the ash or dash shell. However, when launching the command from the Windows cmd shell, the following worked.
cmd /c "C:\cygwin64\bin\ash.exe /usr/rebaseall -v"
-v is to get verbose output
I found another information here :
http://cygwin.com/ml/cygwin/2014-02/msg00531.html
You have to delete the database at
/etc/rebase.db* and do in a "ash" windows :
peflags * -d 1
rebaseall
It works for me on 2 servers.
I solved this problem by restarting my computer. Probably installed a driver update and kept using sleep instead of shutting down.
Experienced the same issue when loading Cygwin with cygiconv-2.dll forking and not loading successfully in the Cygwin terminal, but after turning off my AntiVirus (it was specifically Ad-aware), the issue resolved, and Cygwin worked properly.
In case you are using babun's Cygwin, after rebaseall, try launching Cygwin by executing .babun\cygwin\cygwin.bat in a Windows command prompt or Windows explorer.
This works for me (while launching babun's default console - mintty results in fork error).
I had the error on win10 and i was trying to rebase to c: before install.
then i saw that the installer was installing it instead to c:/Users/myuser
so i was coping all files from c:/Users/myuser to c:.badun
and then restart plus open badun.bat
not shure if this was wise its now duplicated XD... but then it worked again.
Rebaseing didn't help in my case. In addition to what other people suggested, I noticed that reducing the length of PATH environment variable fixed the issue for me (and for other people as well as can be seen from this answer).
This issue is intermittent in nature & I found this issue when there is network is too slow to connect to remote machine on AWS.... I have Shell script that runs through Gitbash shell & it connects to AWS EC2 instance with ssh..... Most of the time, it ran correctly but 2 out 100 times it get into this issue bash: fork: retry: Resource temporarily unavailable .... Killing the MSYS2 terminal from task manager helps to overcome with this issue....
Negative side is you need to run the scripts from the beginning...
I had the same issue on Windows 10 and the mobaxterm app (which uses cygwin) and I tried all of answers listed here however for me, the solution was to simply delete the "CryptoPro CSP" application.
I started facing this problem after upgrading to windows 10. As of now I do not see that any of the above method working.
What I am noticing is that if you start cygwin with admin right (right click and say "run as admin") then it works fine.
Or you open cmd as administrator and then launch cygwin from there, then also it runs fine.
Just reinstall cygwin and select TCL and activate EXPECT
I'm working on implementing a self-updater for a daemon on OS X. The update is published as a .pkg file, so what I'm trying to do is as follows:
When the daemon is notified that an update is available, it calls installer via the system() call to install the package. The package contains a newer version of the daemon, a preupgrade script that stops the daemon (launchctl unload /Library/LaunchDaemons/foo.plist), and a postflight script that starts it back up after the new version is installed. The problem I'm having is that the installer process is quitting prematurely. I suspect that it may be because the installer kills its parent process in order to update it, and then gets killed itself instead of continuing as its own orphan process. I've tried the following with no luck:
Postpending the installer command with '&' to run it in the
background
Wrapping the installer command with nohup
The install command completes consistently without error when I run it from the command line, and fails consistently when run from the installer. When called from the installer, I'm piping the output to a file, and sometimes it has nothing, and sometimes it shows the install getting to about 41% completion before output stops. Any ideas on how I can figure out what's happening to the process or make sure it stays alive without its parent?
When you call launchctl unload, it kills the entire process group (unlike a simple kill). You want to move your subprocess into a separate process group. The easiest way is with the C call setsid().
If you're in the middle of a shell script, you should look at the following approaches. I haven't tried these since I was dealing with a C program and could setsid():
Prior to calling the installer, use set -m. This is supposed to turn on monitor mode, which says "Background processes run in a separate process group and a line containing their exit status is printed upon their completion."
Try this sub-interative shell trick: New process group in shell script