1.Dd Nov 23, 1997 2.Dt TRUSS 1 3.Os FreeBSD 4.Sh NAME 5.Nm truss 6.Nd trace system calls 7.Sh SYNOPSIS 8.Nm truss 9.Op Fl S 10.Op Fl o Ar file 11.Fl p Ar pid 12.Nm truss 13.Op Fl S 14.Op Fl o Ar file 15command 16.Op args 17.Sh DESCRIPTION 18.Nm Truss 19traces the system calls called by the specified process or program. 20Output is to the specified output file, or standard error by default. 21It does this by stopping and restarting the process being monitored via 22.Xr procfs 5 . 23.Pp 24The options are as follows: 25.Bl -tag -width indent 26.It Fl S 27Do not display information about signals received by the process. 28(Normally, 29.Nm 30displays signal as well as system call events.) 31.It Fl o Ar file 32Print the output to the specified 33.Ar file 34instead of standard error. 35.It Fl p Ar pid 36Follow the process specified by 37.Ar pid 38instead of a new command. 39.It Ar command Op args 40Execute 41.Ar command 42and trace the system calls of it. 43(The 44.Fl p 45and 46.Ar command 47options are mutually exclusive.) 48.Sh EXAMPLES 49# Follow the system calls used in echoing "hello" 50.Dl $ truss /bin/echo hello 51# Do the same, but put the output into a file 52.Dl $ truss -o /tmp/truss.out /bin/echo hello 53# Follow an already-running process 54.Dl $ truss -p 1 55.Sh SEE ALSO 56.Xr kdump 1 , 57.Xr ktrace 1 , 58.Xr procfs 5 59.Sh HISTORY 60The 61.Nm 62command was written by 63.An Sean Eric Fagan 64for 65.Bx Free Ns ; 66it was modeled after 67similar commands available for System V Release 4 and SunOS. 68