In general, you can only influence a process’s environment variables at the time the process starts up. If you need to communicate a change to a running process, the environment isn’t the right tool. However, this question has some answers that suggest ways to overcome this limitation. Edited to add in light of discussion in … Read more
Use parameter expansion. ${#chars} is the number of possible characters, % is the modulo operator. ${chars:offset:length} selects the character(s) at position offset, i.e. 0 – length($chars) in our case. chars=abcd1234ABCD for i in {1..8} ; do echo -n “${chars:RANDOM%${#chars}:1}” done echo
Is there a way to force the old behavior? Yes. You can use this option -Wl,–disable-new-dtags to tell the new linker to use the old behavior, i.e. RPATH. Is it possible to tell the old version of linker to produce the new output (i.e. RUNPATH instead of RPATH)? Yes. Use -Wl,–enable-new-dtags to tell the old … Read more
For a joinable (i.e NOT detached) pthread you could use pthread_kill like this: int ret = pthread_kill(YOUR_PTHREAD_ID, 0); If you get a ESRCH value, it might be the case that your thread is dead. However this doesn’t apply to a detached pthreads because after it has ended its thread ID can be reused for another … Read more
This depends in part on your operating system. There is however no limit on a specific port. There is a limit on the number of concurrent connections however, typically limited by the number of file descriptors the kernel supports (eg 2048). The thing to remember is that a TCP connection is unique and a connection … Read more
Another option is to use the prlimit command (from the util-linux package). For example if you want to set the maximum number of open files for a running process to 4096: prlimit -n4096 -p pid_of_process
grep -v -f pattern_file
Under Linux, deamons are simple background processes. No special control methods (e.g start(), stop()) are used as in Windows. Build your service as a simple (console) application, and run it in the background. Use a tool like daemonize to run a program as a Unix daemon, and remember to specify mono as the program to … Read more
Make sure you have a service started and listening on the port. netstat -ln | grep 8080 and sudo netstat -tulpn
If you fork with the purpose of calling an exec function, you can use fcntl with FD_CLOEXEC to have the file descriptor closed once you exec: int fd = open(…); fcntl(fd, F_SETFD, FD_CLOEXEC); Such a file descriptor will survive a fork but not functions of the exec family.