TRUSS(1)

NAME
truss - trace system calls

SYNOPSIS
truss [-S] [-o file] -p pid
truss [-S] [-o file] command [args]

DESCRIPTION
The truss utility traces the system calls called by the specified process or program. Output is to the specified output file, or standard error by default. It does this by stopping and restarting the process being monitored via procfs(5).

The options are as follows:

-S  Do not display information about signals received by the process. (Normally, truss displays signal as well as system call events.)

-o file
    Print the output to the specified file instead of standard error.

-p pid
    Follow the process specified by pid instead of a new command.

command [args]
    Execute command and trace the system calls of it. (The -p and command options are mutually exclusive.)

EXAMPLES
# Follow the system calls used in echoing "hello"
    $ truss /bin/echo hello
# Do the same, but put the output into a file
    $ truss -o /tmp/truss.out /bin/echo hello
# Follow an already-running process
    $ truss -p 1

SEE ALSO
kdump(1), ktrace(1), procfs(5)

HISTORY
The truss command was written by Sean Eric Fagan for FreeBSD. It was modeled after similar commands available for System V Release 4 and SunOS.