Strace

Notes

• strace is a Linux-only program that lists all the system call that a program is doing

• Base usage: strace <program-to-trace> (e.g., strace ls)

• Each line of strace 's output will contain

  • the process ID

  • the name of the system call

  • the system call arguments

  • the return value

• Useful flags:

  • strace -e <system call> <program> will only display the calls to the system call passed as argument (e.g., strace -e open will only list the calls to the open system call)

  • strace -f <program> will follow the subprocesses started by the original program (-f stands for follow)

  • strace -o <output-file> will redirect the output to the specified <output-file>

  • strace -p <pid> will list the system calls for a live process

  • strace -s <num-chars> will show the first <num-chars> characters of each string

  • strace -z will only show system calls that returned without an error code

  • strace -Z will only show system calls that returned with an error code

Resources

Websites

• Julia Evans