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

       -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.

       If you like to report a bug, send a notice to the author,  or  use  the
       bug(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 <cespedes@debian.org>



SEE ALSO

       strace(1), ptrace(2)




                                                                     ltrace(1)

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