1.\" $FreeBSD$ 2.\" 3.Dd January 2, 2004 4.Dt TRUSS 1 5.Os 6.Sh NAME 7.Nm truss 8.Nd trace system calls 9.Sh SYNOPSIS 10.Nm 11.Op Fl faedDS 12.Op Fl o Ar file 13.Op Fl s Ar strsize 14.Fl p Ar pid 15.Nm 16.Op Fl faedDS 17.Op Fl o Ar file 18.Op Fl s Ar strsize 19.Ar command Op Ar args 20.Sh DESCRIPTION 21The 22.Nm 23utility traces the system calls called by the specified process or program. 24Output is to the specified output file, or standard error by default. 25It does this by stopping and restarting the process being monitored via 26.Xr ptrace 2 . 27.Pp 28The options are as follows: 29.Bl -tag -width indent 30.It Fl f 31Trace descendants of the original traced process created by 32.Xr fork 2 , 33.Xr vfork 2 , 34etc. 35.It Fl a 36Show the argument strings that are passed in each 37.Xr execve 2 38system call. 39.It Fl e 40Show the environment strings that are passed in each 41.Xr execve 2 42system call. 43.It Fl d 44Include timestamps in the output showing the time elapsed 45since the trace was started. 46.It Fl D 47Include timestamps in the output showing the time elapsed 48since the last recorded event. 49.It Fl S 50Do not display information about signals received by the process. 51(Normally, 52.Nm 53displays signal as well as system call events.) 54.It Fl o Ar file 55Print the output to the specified 56.Ar file 57instead of standard error. 58.It Fl s Ar strsize 59Display strings using at most 60.Ar strsize 61characters. 62If the buffer is larger, 63.Dq Li ... 64will be displayed at the end of the string. 65The default 66.Ar strsize 67is 32. 68.It Fl p Ar pid 69Follow the process specified by 70.Ar pid 71instead of a new command. 72.It Ar command Op Ar args 73Execute 74.Ar command 75and trace the system calls of it. 76(The 77.Fl p 78and 79.Ar command 80options are mutually exclusive.) 81.El 82.Sh EXAMPLES 83# Follow the system calls used in echoing "hello" 84.Dl $ truss /bin/echo hello 85# Do the same, but put the output into a file 86.Dl $ truss -o /tmp/truss.out /bin/echo hello 87# Follow an already-running process 88.Dl $ truss -p 1 89.Sh SEE ALSO 90.Xr kdump 1 , 91.Xr ktrace 1 , 92.Xr ptrace 2 93.Sh HISTORY 94The 95.Nm 96command was written by 97.An Sean Eric Fagan 98for 99.Fx . 100It was modeled after 101similar commands available for System V Release 4 and SunOS. 102