#strace

strace: See what system calls kernal is executing.

In linux environment when you run any piece of code, any application or software. The piece of code actually maps to the some set of instructions in kernal level. To see those instructions that are being executed for that piece of code we can use this tool called strace. We will see what system calls kernal is executing.

Installation:

sudo apt-get install strace

Usage:

After this is…

Finding problems with strace

I had the fun of trying to find out what was wrong with a long running process – after a day, the process would slow to a halt. I’ve used in a drunken haze in the past a program called strace. This lets you attach to the process and monitors the system calls and signals it makes.

The script is a network and database specific application. I got the process ID from ps aux, and proceeded to attach…

How to invoke the 2nd pass of the clang compiler manually

Because the clang front end reexecs itself, breakpoints on the interesting parts of the clang front end don’t get hit by default. Here’s an example

$ cat g2 b llvm::Module::setDataLayout b BackendConsumer::BackendConsumer b llvm::TargetMachine::TargetMachine b llvm::TargetMachine::createDataLayout run -mbig-endian -m64 -c bytes.c -emit-llvm -o big.bc $ gdb `which clang` GNU gdb (GDB) Red Hat…

To summarise syscalls by time or count, use strace -c. To include child processed, add -f switch. For example: