2a326134d0
type which is a String type that has no -s limitations applied to it. Change most Strings in the code to Names and add a few extra syscalls, namely munmap, read, rename and symlink. This was enough to facilitate following file descriptor allocations in the code more easily and getting a hint at what's being read/written from/to files. More syscalls should really be added. While here, fix an off-by-one bug in the buffer truncation code and add a fflush so that truss's output reflects the syscall that the program is stuck in. Sponsored by: Sophos/Activestate MFC after: 2 weeks
111 lines
2.2 KiB
Groff
111 lines
2.2 KiB
Groff
.\" $FreeBSD$
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.\"
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.Dd September 3, 2004
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.Dt TRUSS 1
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.Os
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.Sh NAME
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.Nm truss
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.Nd trace system calls
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.Sh SYNOPSIS
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.Nm
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.Op Fl faedDS
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.Op Fl o Ar file
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.Op Fl s Ar strsize
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.Fl p Ar pid
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.Nm
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.Op Fl faedDS
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.Op Fl o Ar file
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.Op Fl s Ar strsize
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command
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.Op args
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.Sh DESCRIPTION
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The
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.Nm
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utility traces the system calls called by the specified process or program.
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Output is to the specified output file, or standard error by default.
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It does this by stopping and restarting the process being monitored via
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.Xr procfs 5 .
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl f
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Trace descendants of the original traced process created by
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.Xr fork 2 ,
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.Xr vfork 2 ,
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etc.
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.It Fl a
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Show the argument strings that are passed in each
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.Xr execve 2
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system call.
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.It Fl e
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Show the environment strings that are passed in each
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.Xr execve 2
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system call.
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.It Fl d
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Include timestamps in the output showing the time elapsed
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since the trace was started.
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.It Fl D
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Include timestamps in the output showing the time elapsed
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since the last recorded event.
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.It Fl S
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Do not display information about signals received by the process.
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(Normally,
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.Nm
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displays signal as well as system call events.)
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.It Fl o Ar file
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Print the output to the specified
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.Ar file
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instead of standard error.
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.It Fl s Ar strsize
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Display strings using at most
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.Ar strsize
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characters.
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If the buffer is larger,
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.Qq ...
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will be displayed at the end of the string.
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The default
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.Ar strsize
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is 32.
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.It Fl p Ar pid
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Follow the process specified by
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.Ar pid
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instead of a new command.
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.It Ar command Op args
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Execute
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.Ar command
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and trace the system calls of it.
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(The
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.Fl p
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and
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.Ar command
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options are mutually exclusive.)
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.El
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.Pp
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The
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.Xr procctl 8
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utility can be used to clear tracepoints in a stuck process
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left behind if
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.Nm
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terminates abnormally.
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.Sh EXAMPLES
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# Follow the system calls used in echoing "hello"
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.Dl $ truss /bin/echo hello
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# Do the same, but put the output into a file
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.Dl $ truss -o /tmp/truss.out /bin/echo hello
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# Follow an already-running process
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.Dl $ truss -p 1
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.Sh SEE ALSO
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.Xr kdump 1 ,
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.Xr ktrace 1 ,
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.Xr procfs 5 ,
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.Xr procctl 8
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.Sh HISTORY
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The
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.Nm
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command was written by
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.An Sean Eric Fagan
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for
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.Fx .
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It was modeled after
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similar commands available for System V Release 4 and SunOS.
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