ltrace - A library call tracer
ltrace [-dfiLSrtttChV] [-a column] [-s strsize] [-o filename] [-n nr] [-l filename] [-u
username] [-p pid] ... [-e expr] [--debug] [--demangle] [--align=column] [--output=file-
name] [--indent=nr] [--library=filename] [--help] [--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).
Increase the debugging level. Use more (ie. =dd ) for greater debugging informa-
-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.
-i Print the instruction pointer at the time of the library call.
-L DON'T display library calls (use it with the -S option).
-S Display system calls as well as library calls
-r Print a relative timestamp with each line of the trace. This records the time dif-
ference between the beginning of successive lines.
-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.
Decode (demangle) low-level symbol names into user-level names. Besides removing
any initial underscore prepended by the system, this makes C++ function names read-
-a, --align column
Align return values in a secific column (default column is 5/8 of screen width).
-s Specify the maximum string size to print (the default is 32).
-o, --output filename
Write the trace output to the file filename rather than to stderr.
-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.
-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.
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.
-p pid Attach to the process with the process ID pid and begin tracing.
A qualifying expression which modifies which events to trace. The format of the
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 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.
Show a summary of the options to ltrace and exit.
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/i386, Linux/m68k, Linux/arm, and Linux/S390.
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>