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       ltrace - A library call tracer


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


       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 ("...")

       -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 level
              Show debugging output of ltrace itself.  level must be a sum  of
              some of the following numbers:

              01     DEBUG_GENERAL.  Shows helpful progress information

              010    DEBUG_EVENT.   Shows  every  event  received  by a traced

              020    DEBUG_PROCESS.  Shows every action ltrace carries upon  a
                     traced process

              040    DEBUG_FUNCTION.  Shows every entry to internal functions

       -e expr
              A  qualifying  expression  which modifies which events to trace.
              The format of the expression is:
              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

              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 immediately.

       -F     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.

       -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 30 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

       -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

       -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.

       -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

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


       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  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 <>


       strace(1), ptrace(2)