ltrace

ltrace(1)							    ltrace(1)



NAME
       ltrace - A library call tracer


SYNOPSIS
       ltrace [-CdfhiLrStttV] [-a column] [-e expr] [-l filename] [-n nr] [-o
       filename] [-p pid] ... [-s strsize]  [-u	 username]  [-X	 extern]  [-x
       extern]	 ...   [--align=column]	  [--debug]   [--demangle]   [--help]
       [--indent=nr]  [--library=filename]  [--output=filename]	  [--version]
       [command [arg ...]]


DESCRIPTION
       ltrace  is  a  program that simply runs the specified command until it
       exits.  It intercepts and records the dynamic library calls which  are
       called  by  the executed process and the signals which are received by
       that process.  It can also intercept and print the system  calls	 exe-
       cuted by the program.

       Its use is very similar to strace(1).


OPTIONS
       -a, --align column
	      Align  return values in a secific column (default column is 5/8
	      of screen width).

       -c     Count time and calls for each library call and report a summary
	      on program exit.

       -C, --demangle
	      Decode (demangle) low-level symbol names into user-level names.
	      Besides removing any initial underscore prepended by  the	 sys-
	      tem, this makes C++ function names readable.

       -d, --debug
	      Increase the debugging level.  Use more (ie.  -dd ) for greater
	      debugging information.

       -e expr
	      A qualifying expression which modifies which events  to  trace.
	      The format of the expression is:
	      [!]value1[,value2]...
	      where the values are the functions to trace.  Using an exclama-
	      tion mark negates the set of values.   For  example  -e  printf
	      means  to	 trace only the printf library call.  By contrast, -e
	      !printf means to trace every library call except printf.

	      Note that some shells use the  exclamation  point	 for  history
	      expansion;  even	inside	quoted	arguments.   If	 so, you must
	      escape the exclamation point with a backslash.

       -f     Trace child processes as they are created by currently   traced
	      processes	 as a result of the fork(2) or clone(2) system calls.
	      The new process is attached as soon as its pid is known.

       -h, --help
	      Show a summary of the options to ltrace and exit.

       -i     Print the instruction pointer at the time of the library	call.

       -l, --library filename
	      Display  only the symbols included in the library filename.  Up
	      to 20 library names can be specified with several instances  of
	      this option.

       -L     DON’T display library calls (use it with the -S option).

       -n, --indent nr
	      Indent  trace output by nr number of spaces for each new nested
	      call. Using this option makes the	 program  flow	visualization
	      easy to follow.

       -o, --output filename
	      Write  the  trace	 output	 to  the file filename rather than to
	      stderr.

       -p pid Attach to the process with the process ID pid and	 begin	trac-
	      ing.

       -r     Print  a	relative timestamp with each line of the trace.	 This
	      records the time difference between the beginning of successive
	      lines.

       -s strsize
	      Specify the maximum string size to print (the default is 32).

       -S     Display system calls as well as library calls

       -t     Prefix each line of the trace with the time of day.

       -tt    If given twice, the time printed will include the microseconds.

       -ttt   If given thrice, the time printed will include the microseconds
	      and  the	leading portion will be printed as the number of sec-
	      onds since the epoch.

       -T     Show  the	 time  spent inside each call. This records the	 time
	      difference between the beginning and the end of each call.

       -u username
	      Run  command  with the userid, groupid and supplementary groups
	      of username.  This option is only useful when running  as	 root
	      and enables the correct execution of setuid and/or setgid bina-
	      ries.

       -X extern
	      Some architectures need to know where to set a breakpoint	 that
	      will  be hit after the dynamic linker has run.  If this flag is
	      used, then the breakpoint is set at extern, which	 must  be  an
	      external function.  By default, ’main’ is used.

       -x extern
	      Trace  the  external  function  extern.	This  option  may  be
	      repeated.

       -V, --version
	      Show the version number of ltrace and exit.


BUGS
       It has most of the bugs stated in strace(1).

       Manual page and documentation are not very up-to-date.

       Option -f sometimes fails to trace some children.

       It only works on Linux and in a small subset of architectures.

       Only ELF32 binaries are supported.

       Calls to dlopen()ed libraries will not be traced.

       If you like to report a bug, send a notice to the author, or  use  the
       reportbug(1)  program  if you are under the Debian GNU/Linux distribu-
       tion.


FILES
       /etc/ltrace.conf
	      System configuration file

       ~/.ltrace.conf
	      Personal config file, overrides /etc/ltrace.conf


AUTHOR
       Juan Cespedes <cespedes@debian.org>


SEE ALSO
       strace(1), ptrace(2)




								    ltrace(1)