SIGTERM and SIGKILL are intended for general purpose “terminate this process” requests. SIGTERM (by default) and SIGKILL (always) will cause process termination. SIGTERM may be caught by the process (e.g. so that it can do its own cleanup if it wants to), or even ignored completely; but SIGKILL cannot be caught or ignored. SIGINT and … Read more
fsync() returns -EIO if the kernel lost a write (Note: early part references older kernels; updated below to reflect modern kernels) It looks like async buffer write-out in end_buffer_async_write(…) failures set an -EIO flag on the failed dirty buffer page for the file: set_bit(AS_EIO, &page->mapping->flags); set_buffer_write_io_error(bh); clear_buffer_uptodate(bh); SetPageError(page); which is then detected by wait_on_page_writeback_range(…) as … Read more
Use sigaction() unless you’ve got very compelling reasons not to do so. The signal() interface has antiquity (and hence availability) in its favour, and it is defined in the C standard. Nevertheless, it has a number of undesirable characteristics that sigaction() avoids – unless you use the flags explicitly added to sigaction() to allow it … Read more
The distinction between a real and an effective user id is made because you may have the need to temporarily take another user’s identity (most of the time, that would be root, but it could be any user). If you only had one user id, then there would be no way of changing back to … Read more
Add @ to the beginning of command to tell gmake not to print the command being executed. Like this: run: @java myprogram As Oli suggested, this is a feature of Make and not of Bash. On the other hand, Bash will never echo commands being executed unless you tell it to do so explicitly (i.e. … Read more
The sleep man page says it is declared in <unistd.h>. Synopsis: #include <unistd.h> unsigned int sleep(unsigned int seconds);
signal isn’t the most reliable way as it differs in implementations. I would recommend using sigaction. Tom’s code would now look like this : #include <signal.h> #include <stdlib.h> #include <stdio.h> #include <unistd.h> void my_handler(int s){ printf(“Caught signal %d\n”,s); exit(1); } int main(int argc,char** argv) { struct sigaction sigIntHandler; sigIntHandler.sa_handler = my_handler; sigemptyset(&sigIntHandler.sa_mask); sigIntHandler.sa_flags = 0; … Read more
Add -lrt to the end of g++ command line. This links in the librt.so “Real Time” shared library.
Defining _GNU_SOURCE has nothing to do with license and everything to do with writing (non-)portable code. If you define _GNU_SOURCE, you will get: access to lots of nonstandard GNU/Linux extension functions access to traditional functions which were omitted from the POSIX standard (often for good reason, such as being replaced with better alternatives, or being … Read more
The proper function is int fileno(FILE *stream). It can be found in <stdio.h>, and is a POSIX standard but not standard C.