ltrace - A library call tracer
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 ...]]
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).
-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.
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.
Increase the debugging level. Use more (ie. =dd ) for greater
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 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.
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
-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
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.
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.
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.
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.
System configuration file
Personal config file, overrides /etc/ltrace.conf
Juan Cespedes <email@example.com>
Man(1) output converted with