ltrace(1)

1ltrace(1)                   General Commands Manual                  ltrace(1)
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NAME

6       ltrace - A library call tracer
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SYNOPSIS

10       ltrace  [-CdfhiLrStttV] [-a column] [-e expr] [-l filename] [-n nr] [-o
11       filename] [-p pid] ... [-s  strsize]  [-u  username]  [-X  extern]  [-x
12       extern]    ...   [--align=column]   [--debug]   [--demangle]   [--help]
13       [--indent=nr]  [--library=filename]   [--output=filename]   [--version]
14       [command [arg ...]]
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DESCRIPTION

18       ltrace  is  a  program  that simply runs the specified command until it
19       exits.  It intercepts and records the dynamic library calls  which  are
20       called  by  the  executed process and the signals which are received by
21       that process.  It can also intercept and print the  system  calls  exe‐
22       cuted by the program.
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24       Its use is very similar to strace(1).
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OPTIONS

28       -a, --align column
29              Align  return values in a specific column (default column is 5/8
30              of screen width).
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32       -c     Count time and calls for each library call and report a  summary
33              on program exit.
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35       -C, --demangle
36              Decode  (demangle) low-level symbol names into user-level names.
37              Besides removing any initial underscore prepended by the system,
38              this makes C++ function names readable.
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40       -d, --debug
41              Increase  the debugging level.  Use more (ie.  -dd ) for greater
42              debugging information.
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44       -e expr
45              A qualifying expression which modifies which  events  to  trace.
46              The format of the expression is:
47              [!]value1[,value2]...
48              where  the values are the functions to trace.  Using an exclama‐
49              tion mark negates the set of  values.   For  example  -e  printf
50              means  to  trace  only the printf library call.  By contrast, -e
51              !printf means to trace every library call except printf.
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53              Note that some shells use  the  exclamation  point  for  history
54              expansion; even inside quoted arguments.  If so, you must escape
55              the exclamation point with a backslash.
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57       -f     Trace child processes as they are created by  currently   traced
58              processes  as  a result of the fork(2) or clone(2) system calls.
59              The new process is attached as soon as its pid is known.
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61       -h, --help
62              Show a summary of the options to ltrace and exit.
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64       -i     Print the instruction pointer at the time of the library call.
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66       -l, --library filename
67              Display only the symbols included in the library  filename.   Up
68              to  20  library names can be specified with several instances of
69              this option.
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71       -L     DON'T display library calls (use it with the -S option).
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73       -n, --indent nr
74              Indent trace output by nr number of spaces for each  new  nested
75              call.  Using  this  option  makes the program flow visualization
76              easy to follow.
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78       -o, --output filename
79              Write the trace output to  the  file  filename  rather  than  to
80              stderr.
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82       -p pid Attach to the process with the process ID pid and begin tracing.
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84       -r     Print  a  relative  timestamp with each line of the trace.  This
85              records the time difference between the beginning of  successive
86              lines.
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88       -s strsize
89              Specify the maximum string size to print (the default is 32).
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91       -S     Display system calls as well as library calls
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93       -t     Prefix each line of the trace with the time of day.
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95       -tt    If given twice, the time printed will include the microseconds.
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97       -ttt   If  given thrice, the time printed will include the microseconds
98              and the leading portion will be printed as the number of seconds
99              since the epoch.
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101       -T     Show   the   time  spent inside each call. This records the time
102              difference between the beginning and the end of each call.
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104       -u username
105              Run command with the userid, groupid and supplementary groups of
106              username.   This  option is only useful when running as root and
107              enables the correct execution of setuid and/or setgid binaries.
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109       -X extern
110              Some architectures need to know where to set a  breakpoint  that
111              will  be  hit after the dynamic linker has run.  If this flag is
112              used, then the breakpoint is set at extern,  which  must  be  an
113              external  function.   By  default, '_start' is used.  NOTE: this
114              flag is only available on the architectures that need it.
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116       -x extern
117              Trace  the  external  function  extern.   This  option  may   be
118              repeated.
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120       -V, --version
121              Show the version number of ltrace and exit.
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BUGS

125       It has most of the bugs stated in strace(1).
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127       Manual page and documentation are not very up-to-date.
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129       Option -f sometimes fails to trace some children.
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131       It only works on Linux and in a small subset of architectures.
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133       Calls to dlopen()ed libraries will not be traced.
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135       If  you  like  to report a bug, send a notice to the author, or use the
136       reportbug(1) program if you are under the  Debian  GNU/Linux  distribu‐
137       tion.
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FILES

141       /etc/ltrace.conf
142              System configuration file
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144       ~/.ltrace.conf
145              Personal config file, overrides /etc/ltrace.conf
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AUTHOR

149       Juan Cespedes <cespedes@debian.org>
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