strace, an useful diagnostic toolstrace

You will always occours some boring situation when using Linux-like system. For example, when you are trying the new feature of emacs unicode branch, such as xft fonts supporting. You input the command "emacs --enable-font-backend -fn monospace", and wish to enjoy the rounded and smooth fonts. However, your Emacs could not start up, and throwed out a fault, like "Fatal error (11)Segmentation fault". If you are a newbie, You may be distracted and donnot how to resolve.

Now, there is a cute tool, strace, to help us diagnose where it crashes. strace can be binded on an existed PID, and trace its system calls. here are some useful arguments:

-f : trace current process and its sub-processes -o file : redirect the output into a file, but not stderr -p pid : bind on a process with pid, which is often used to debug on background.

Here is an example to trace the emacs process, the result will be written into the file emacs.strace.

strace -f -o emacs.strace emacs

Here is an advanced article to explain how strace to work: http://www.linuxforum.net/forum/showflat.php?Cat=&Board=security&Number=534712&page=0&view=collapsed&sb=5&o=31&fpart=