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]  [--out-
       put=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 executed by the program.

       Its use is very similar to strace(1).


OPTIONS
       -a, --align column
              Align return values in a specific 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 system, 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 exclamation 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 tracing.

       -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 seconds 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 run-
              ning as root and enables the correct execution of setuid and/or setgid binaries.

       -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, '_start'
              is used.  NOTE: this flag is only available on the architectures that need it.

       -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.

       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 distribution.


FILES
       /etc/ltrace.conf
              System configuration file

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


AUTHOR
       Juan Cespedes <cespedesATdebian.org>


SEE ALSO
       strace(1), ptrace(2)




                                                                                                                       ltrace(1)