Provided by: ltrace_0.7.3-6.1ubuntu6.22.04.1_amd64 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

       -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

              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 @MAIN.

       -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 stderr.

       -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 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 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 time.

       -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 given.

       -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

       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

       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  (ltrace-,  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)