Provided by: ltrace_0.7.3-5.1ubuntu4_i386 bug


       ltrace - A library call tracer


       ltrace  [-e  filter|-L] [-l|--library=library_pattern] [-x filter] [-S]
       [-b|--no-signals]  [-i]  [-w|--where=nr]  [-r|-t|-tt|-ttt]   [-T]   [-F
       filename] [-A maxelts] [-s strsize] [-C|--demangle] [-a|--align column]
       [-n|--indent nr] [-o|--output filename] [-D|--debug mask] [-u username]
       [-f] [-p pid] [[--] command [arg ...]]

       ltrace  -c  [-e  filter|-L]  [-l|--library=library_pattern] [-x filter]
       [-S] [-o|--output filename] [-f] [-p pid] [[--] command [arg ...]]

       ltrace -V|--version

       ltrace -h|--help


       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).


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

       -A maxelts
              Maximum number of array elements to print before suppressing the
              rest with an ellipsis  ("...").   This  also  limits  number  of
              recursive structure expansions.

       -b, --no-signals
              Disable printing of signals recieved by the traced process.

       -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  prefix  used by the
              system, this makes C++ function names readable.

       -D, --debug mask
              Show debugging output of ltrace itself.  mask is a  number  with
              internal meaning that's not really well defined at all.  mask of
              77 shows all debug messages, which is what you usually need.

       -e filter
              A qualifying expression which modifies which  library  calls  to
              trace.   The format of the filter expression is described in the
              section FILTER EXPRESSIONS.  If more than one -e option  appears
              on  the  command  line, the library calls that match any of them
              are traced.  If no -e is given, @MAIN is assumed as a default.

       -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 immediately.

       -F filename
              Load an alternate config file.  Normally,  /etc/ltrace.conf  and
              ~/.ltrace.conf will be read (the latter only if it exists).  Use
              this option to load the given file or files instead of those two
              default  files.  See ltrace.conf(5) for details on the syntax of
              ltrace configuration files.

       -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 library_pattern
              Display only calls to functions implemented  by  libraries  that
              match   library_pattern.    Multiple   library  patters  can  be
              specified with several instances  of  this  option.   Syntax  of
              library_pattern is described in section FILTER EXPRESSIONS.

              Note that while this option selects calls that might be directed
              to the selected libraries, there's no actual guarantee that  the
              call  won't  be  directed  elsewhere  due  to e.g. LD_PRELOAD or
              simply dependency ordering.  If  you  want  to  make  sure  that
              symbols   in   given   library   are  actually  called,  use  -x
              @library_pattern instead.

       -L     When no -e option is given, don't assume the default  action  of

       -n, --indent nr
              Indent trace output by nr spaces for each level of call nesting.
              Using this option makes the program flow visualization  easy  to
              follow.   This  indents  uselessly  also  functions  that  never
              return, such as service functions for throwing exceptions in the
              C++ runtime.

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

       -p pid Attach to the process with the process ID pid and begin tracing.
              This  option  can  be  used  together  with passing a command to
              execute.  It is possible  to  attach  to  several  processes  by
              passing more than one option -p.

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

       -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 running as root and
              enables the correct execution of setuid and/or setgid binaries.

       -w, --where nr
              Show backtrace of nr stack frames for each traced function. This
              option  enabled only if libunwind support was enabled at compile

       -x filter
              A qualifying expression which modifies which symbol table  entry
              points  to  trace.   The  format  of  the  filter  expression is
              described in the section FILTER EXPRESSIONS.  If more  than  one
              -x  option  appears  on the command line, the symbols that match
              any of them are traced.  No entry points are traced if no -x  is

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


       Filter  expression  is  a chain of glob- or regexp-based rules that are
       used to pick symbols for tracing from libraries that the process  uses.
       Most  of  it  is intuitive, so as an example, the following would trace
       calls to malloc and free, except those done by libc:


       This reads: trace malloc and free, but don't trace anything that  comes
       from  libc.   Semi-formally,  the  syntax  of  the  above example looks
       approximately like this:


       Symbol_pattern is used to match symbol names, library_pattern to  match
       library  SONAMEs.   Both  are  implicitly  globs,  but  can  be regular
       expressions as well  (see  below).   The  glob  syntax  supports  meta-
       characters  * and ? and character classes, similarly to what basic bash
       globs support.  ^ and $ are recognized to mean, respectively, start and
       end of given name.

       Both  symbol_pattern  and library_pattern have to match the whole name.
       If you want to match only part of the name, surround it with one or two
       *'s  as  appropriate.  The exception is if the pattern is not mentioned
       at all, in which case it's as if the corresponding pattern were *.  (So
       malloc is really malloc@* and @libc.* is really *@libc.*.)

       In  libraries that don't have an explicit SONAME, basename is taken for
       SONAME.  That holds for main binary as well: /bin/echo has an  implicit
       SONAME  of  echo.   In  addition  to that, special library pattern MAIN
       always matches symbols in the main binary  and  never  a  library  with
       actual SONAME MAIN (use e.g. ^MAIN or [M]AIN for that).

       If  the  symbol  or  library  pattern  is  surrounded in slashes (/like
       this/), then it is considered  a  regular  expression  instead.   As  a
       shorthand, instead of writing /x/@/y/, you can write /x@y/.

       If  the  library  pattern  starts  with  a  slash,  it  is not a SONAME
       expression, but a path expression, and is matched against  the  library
       path name.

       The first rule may lack a sign, in which case + is assumed.  If, on the
       other hand, the first rule has a - sign, it is as if there was  another
       rule  @  in  front of it, which has the effect of tracing complement of
       given rule.

       The above rules are used to construct the set of traced symbols.   Each
       candidate   symbol   is  passed  through  the  chain  of  above  rules.
       Initially, the symbol is unmarked.  If it matches a + rule, it  becomes
       marked,  if  it matches a - rule, it becomes unmarked again.  If, after
       applying all rules, the symbol is marked, it will be traced.


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

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

       If you would like to report a bug, send a message to the  mailing  list
       (, or use the reportbug(1) program
       if you are under the Debian GNU/Linux distribution.


              System configuration file

              Personal config file, overrides /etc/ltrace.conf


       Juan Cespedes <>
       Petr Machata <>


       ltrace.conf(5), strace(1), ptrace(2)

                                 January 2013                        LTRACE(1)