truss -- trace system calls
truss [-faedDS] [-o file] -p pid
truss [-faedDS] [-o file] command [args]
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
The options are as follows:
-f Trace decendants of the original traced process created by
fork(2), vfork(2), etc.
-a Show the argument strings that are passed in each execve(2) system
-e Show the environment strings that are passed in each execve(2)
-d Include timestamps in the output showing the time elapsed since
the trace was started.
-D Include timestamps in the output showing the time elapsed since
the last recorded event.
-S Do not display information about signals received by the process.
(Normally, truss displays signal as well as system call events.)
Print the output to the specified file instead of standard error.
-p pid Follow the process specified by pid instead of a new command.
Execute command and trace the system calls of it. (The -p and
command options are mutually exclusive.)
# 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
kdump(1), ktrace(1), procfs(5)
The truss command was written by Sean Eric Fagan for FreeBSD. It was
modeled after similar commands available for System V Release 4 and
FreeBSD 5.2.1 November 23, 1997 FreeBSD 5.2.1 [ Back ]