{ "content": [ { "type": "text", "text": "# ltrace (man)\n\n## NAME\n\nltrace - A library call tracer\n\n## SYNOPSIS\n\nltrace [-e filter|-L] [-l|--library=librarypattern] [-x filter] [-S] [-b|--no-signals] [-i]\n[-w|--where=nr] [-r|-t|-tt|-ttt] [-T] [-F filename] [-A maxelts] [-s strsize] [-C|--demangle]\n[-a|--align column] [-n|--indent nr] [-o|--output filename] [-D|--debug mask] [-u username]\n[-f] [-p pid] [[--] command [arg ...]]\nltrace -c [-e filter|-L] [-l|--library=librarypattern] [-x filter] [-S] [-o|--output file‐\nname] [-f] [-p pid] [[--] command [arg ...]]\nltrace -V|--version\nltrace -h|--help\n\n## DESCRIPTION\n\nltrace is a program that simply runs the specified command until it exits. It intercepts and\nrecords the dynamic library calls which are called by the executed process and the signals\nwhich are received by that process. It can also intercept and print the system calls exe‐\ncuted by the program.\n\n## TLDR\n\n> Display dynamic library calls of a process.\n\n- Print (trace) library calls of a program binary:\n `ltrace {{path/to/program}}`\n- Count library calls. Print a handy summary at the bottom:\n `ltrace -c {{path/to/program}}`\n- Trace calls to malloc and free, omit those done by libc:\n `ltrace -e malloc+free-@libc.so* {{path/to/program}}`\n- Write to file instead of terminal:\n `ltrace {{-o|--output}} {{file}} {{path/to/program}}`\n\n*Source: tldr-pages*\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION**\n- **OPTIONS** (4 subsections)\n- **FILTER EXPRESSIONS**\n- **BUGS**\n- **FILES**\n- **AUTHOR**\n- **SEE ALSO**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "ltrace", "section": "", "mode": "man", "summary": "ltrace - A library call tracer", "synopsis": "ltrace [-e filter|-L] [-l|--library=librarypattern] [-x filter] [-S] [-b|--no-signals] [-i]\n[-w|--where=nr] [-r|-t|-tt|-ttt] [-T] [-F filename] [-A maxelts] [-s strsize] [-C|--demangle]\n[-a|--align column] [-n|--indent nr] [-o|--output filename] [-D|--debug mask] [-u username]\n[-f] [-p pid] [[--] command [arg ...]]\nltrace -c [-e filter|-L] [-l|--library=librarypattern] [-x filter] [-S] [-o|--output file‐\nname] [-f] [-p pid] [[--] command [arg ...]]\nltrace -V|--version\nltrace -h|--help", "tldr_summary": "Display dynamic library calls of a process.", "tldr_examples": [ { "description": "Print (trace) library calls of a program binary", "command": "ltrace {{path/to/program}}" }, { "description": "Count library calls. Print a handy summary at the bottom", "command": "ltrace -c {{path/to/program}}" }, { "description": "Trace calls to malloc and free, omit those done by libc", "command": "ltrace -e malloc+free-@libc.so* {{path/to/program}}" }, { "description": "Write to file instead of terminal", "command": "ltrace {{-o|--output}} {{file}} {{path/to/program}}" } ], "tldr_source": "official", "flags": [ { "flag": "-b", "long": "--no-signals", "arg": null, "description": "Disable printing of signals recieved by the traced process. -c Count time and calls for each library call and report a summary on program exit." }, { "flag": "-C", "long": "--demangle", "arg": null, "description": "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 mask Show debugging output of ltrace itself. mask is a number with internal meaning that's not really well defined at all. mask of 77 shows all debug messages, which is what you usually need. -e filter A qualifying expression which modifies which library calls to trace. The format of the filter expression is described in the section FILTER EXPRESSIONS. If more than one -e option appears on the command line, the library calls that match any of them are traced. If no -e is given, @MAIN is assumed as a default. -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 filename 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. See ltrace.conf(5) for details on the syntax of ltrace configuration files." }, { "flag": "-h", "long": "--help", "arg": null, "description": "Show a summary of the options to ltrace and exit. -i Print the instruction pointer at the time of the library call. -l, --library librarypattern Display only calls to functions implemented by libraries that match librarypattern. Multiple library patters can be specified with several instances of this option. Syn‐ tax of librarypattern is described in section FILTER EXPRESSIONS. Note that while this option selects calls that might be directed to the selected li‐ braries, there's no actual guarantee that the call won't be directed elsewhere due to e.g. LDPRELOAD or simply dependency ordering. If you want to make sure that symbols in given library are actually called, use -x @librarypattern instead. -L When no -e option is given, don't assume the default action of @MAIN. -n, --indent nr Indent trace output by nr spaces for each level of call nesting. Using this option makes the program flow visualization easy to follow. This indents uselessly also functions that never return, such as service functions for throwing exceptions in the C++ runtime. -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. This option can be used together with passing a command to execute. It is possible to attach to several processes by passing more than one option -p. -r Print a relative timestamp with each line of the trace. This records the time differ‐ ence 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 por‐ tion 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 op‐ tion is only useful when running as root and enables the correct execution of setuid and/or setgid binaries. -w, --where nr Show backtrace of nr stack frames for each traced function. This option enabled only if libunwind support was enabled at compile time. -x filter A qualifying expression which modifies which symbol table entry points to trace. The format of the filter expression is described in the section FILTER EXPRESSIONS. If more than one -x option appears on the command line, the symbols that match any of them are traced. No entry points are traced if no -x is given." }, { "flag": "-V", "long": "--version", "arg": null, "description": "Show the version number of ltrace and exit." } ], "examples": [], "see_also": [ { "name": "ltrace.conf", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/ltrace.conf/5/json" }, { "name": "strace", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/strace/1/json" }, { "name": "ptrace", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/ptrace/2/json" } ], "section_outline": [ { "name": "NAME", "lines": 3, "subsections": [] }, { "name": "SYNOPSIS", "lines": 13, "subsections": [] }, { "name": "DESCRIPTION", "lines": 8, "subsections": [] }, { "name": "OPTIONS", "lines": 7, "subsections": [ { "name": "-b, --no-signals", "lines": 4, "flag": "-b", "long": "--no-signals" }, { "name": "-C, --demangle", "lines": 23, "flag": "-C", "long": "--demangle" }, { "name": "-h, --help", "lines": 62, "flag": "-h", "long": "--help" }, { "name": "-V, --version", "lines": 3, "flag": "-V", "long": "--version" } ] }, { "name": "FILTER EXPRESSIONS", "lines": 43, "subsections": [] }, { "name": "BUGS", "lines": 9, "subsections": [] }, { "name": "FILES", "lines": 7, "subsections": [] }, { "name": "AUTHOR", "lines": 4, "subsections": [] }, { "name": "SEE ALSO", "lines": 5, "subsections": [] } ], "sections": { "NAME": { "content": "ltrace - A library call tracer\n\n", "subsections": [] }, "SYNOPSIS": { "content": "ltrace [-e filter|-L] [-l|--library=librarypattern] [-x filter] [-S] [-b|--no-signals] [-i]\n[-w|--where=nr] [-r|-t|-tt|-ttt] [-T] [-F filename] [-A maxelts] [-s strsize] [-C|--demangle]\n[-a|--align column] [-n|--indent nr] [-o|--output filename] [-D|--debug mask] [-u username]\n[-f] [-p pid] [[--] command [arg ...]]\n\nltrace -c [-e filter|-L] [-l|--library=librarypattern] [-x filter] [-S] [-o|--output file‐\nname] [-f] [-p pid] [[--] command [arg ...]]\n\nltrace -V|--version\n\nltrace -h|--help\n\n", "subsections": [] }, "DESCRIPTION": { "content": "ltrace is a program that simply runs the specified command until it exits. It intercepts and\nrecords the dynamic library calls which are called by the executed process and the signals\nwhich are received by that process. It can also intercept and print the system calls exe‐\ncuted by the program.\n\nIts use is very similar to strace(1).\n\n", "subsections": [] }, "OPTIONS": { "content": "-a, --align column\nAlign return values in a specific column (default column is 5/8 of screen width).\n\n-A maxelts\nMaximum number of array elements to print before suppressing the rest with an ellipsis\n(\"...\"). This also limits number of recursive structure expansions.\n", "subsections": [ { "name": "-b, --no-signals", "content": "Disable printing of signals recieved by the traced process.\n\n-c Count time and calls for each library call and report a summary on program exit.\n", "flag": "-b", "long": "--no-signals" }, { "name": "-C, --demangle", "content": "Decode (demangle) low-level symbol names into user-level names. Besides removing any\ninitial underscore prefix used by the system, this makes C++ function names readable.\n\n-D, --debug mask\nShow debugging output of ltrace itself. mask is a number with internal meaning that's\nnot really well defined at all. mask of 77 shows all debug messages, which is what\nyou usually need.\n\n-e filter\nA qualifying expression which modifies which library calls to trace. The format of\nthe filter expression is described in the section FILTER EXPRESSIONS. If more than\none -e option appears on the command line, the library calls that match any of them\nare traced. If no -e is given, @MAIN is assumed as a default.\n\n-f Trace child processes as they are created by currently traced processes as a result of\nthe fork(2) or clone(2) system calls. The new process is attached immediately.\n\n-F filename\nLoad an alternate config file. Normally, /etc/ltrace.conf and ~/.ltrace.conf will be\nread (the latter only if it exists). Use this option to load the given file or files\ninstead of those two default files. See ltrace.conf(5) for details on the syntax of\nltrace configuration files.\n", "flag": "-C", "long": "--demangle" }, { "name": "-h, --help", "content": "Show a summary of the options to ltrace and exit.\n\n-i Print the instruction pointer at the time of the library call.\n\n-l, --library librarypattern\nDisplay only calls to functions implemented by libraries that match librarypattern.\nMultiple library patters can be specified with several instances of this option. Syn‐\ntax of librarypattern is described in section FILTER EXPRESSIONS.\n\nNote that while this option selects calls that might be directed to the selected li‐\nbraries, there's no actual guarantee that the call won't be directed elsewhere due to\ne.g. LDPRELOAD or simply dependency ordering. If you want to make sure that symbols\nin given library are actually called, use -x @librarypattern instead.\n\n-L When no -e option is given, don't assume the default action of @MAIN.\n\n-n, --indent nr\nIndent trace output by nr spaces for each level of call nesting. Using this option\nmakes the program flow visualization easy to follow. This indents uselessly also\nfunctions that never return, such as service functions for throwing exceptions in the\nC++ runtime.\n\n-o, --output filename\nWrite the trace output to the file filename rather than to stderr.\n\n-p pid Attach to the process with the process ID pid and begin tracing. This option can be\nused together with passing a command to execute. It is possible to attach to several\nprocesses by passing more than one option -p.\n\n-r Print a relative timestamp with each line of the trace. This records the time differ‐\nence between the beginning of successive lines.\n\n-s strsize\nSpecify the maximum string size to print (the default is 32).\n\n-S Display system calls as well as library calls\n\n-t Prefix each line of the trace with the time of day.\n\n-tt If given twice, the time printed will include the microseconds.\n\n-ttt If given thrice, the time printed will include the microseconds and the leading por‐\ntion will be printed as the number of seconds since the epoch.\n\n-T Show the time spent inside each call. This records the time difference between the\nbeginning and the end of each call.\n\n-u username\nRun command with the userid, groupid and supplementary groups of username. This op‐\ntion is only useful when running as root and enables the correct execution of setuid\nand/or setgid binaries.\n\n-w, --where nr\nShow backtrace of nr stack frames for each traced function. This option enabled only\nif libunwind support was enabled at compile time.\n\n-x filter\nA qualifying expression which modifies which symbol table entry points to trace. The\nformat of the filter expression is described in the section FILTER EXPRESSIONS. If\nmore than one -x option appears on the command line, the symbols that match any of\nthem are traced. No entry points are traced if no -x is given.\n", "flag": "-h", "long": "--help" }, { "name": "-V, --version", "content": "Show the version number of ltrace and exit.\n\n", "flag": "-V", "long": "--version" } ] }, "FILTER EXPRESSIONS": { "content": "Filter expression is a chain of glob- or regexp-based rules that are used to pick symbols for\ntracing from libraries that the process uses. Most of it is intuitive, so as an example, the\nfollowing would trace calls to malloc and free, except those done by libc:\n\n-e malloc+free-@libc.so*\n\nThis reads: trace malloc and free, but don't trace anything that comes from libc. Semi-for‐\nmally, the syntax of the above example looks approximately like this:\n\n{[+-][symbolpattern][@librarypattern]}\n\nSymbolpattern is used to match symbol names, librarypattern to match library SONAMEs. Both\nare implicitly globs, but can be regular expressions as well (see below). The glob syntax\nsupports meta-characters * and ? and character classes, similarly to what basic bash globs\nsupport. ^ and $ are recognized to mean, respectively, start and end of given name.\n\nBoth symbolpattern and librarypattern have to match the whole name. If you want to match\nonly part of the name, surround it with one or two *'s as appropriate. The exception is if\nthe pattern is not mentioned at all, in which case it's as if the corresponding pattern were\n*. (So malloc is really malloc@* and @libc.* is really *@libc.*.)\n\nIn libraries that don't have an explicit SONAME, basename is taken for SONAME. That holds\nfor main binary as well: /bin/echo has an implicit SONAME of echo. In addition to that, spe‐\ncial library pattern MAIN always matches symbols in the main binary and never a library with\nactual SONAME MAIN (use e.g. ^MAIN or [M]AIN for that).\n\nIf the symbol or library pattern is surrounded in slashes (/like this/), then it is consid‐\nered a regular expression instead. As a shorthand, instead of writing /x/@/y/, you can write\n/x@y/.\n\nIf the library pattern starts with a slash, it is not a SONAME expression, but a path expres‐\nsion, and is matched against the library path name.\n\nThe first rule may lack a sign, in which case + is assumed. If, on the other hand, the first\nrule has a - sign, it is as if there was another rule @ in front of it, which has the effect\nof tracing complement of given rule.\n\nThe above rules are used to construct the set of traced symbols. Each candidate symbol is\npassed through the chain of above rules. Initially, the symbol is unmarked. If it matches a\n+ rule, it becomes marked, if it matches a - rule, it becomes unmarked again. If, after ap‐\nplying all rules, the symbol is marked, it will be traced.\n\n", "subsections": [] }, "BUGS": { "content": "It has most of the bugs stated in strace(1).\n\nIt only works on Linux and in a small subset of architectures.\n\nIf you would like to report a bug, send a message to the mailing list (ltrace-de‐\nvel@lists.alioth.debian.org), or use the reportbug(1) program if you are under the Debian\nGNU/Linux distribution.\n\n", "subsections": [] }, "FILES": { "content": "/etc/ltrace.conf\nSystem configuration file\n\n~/.ltrace.conf\nPersonal config file, overrides /etc/ltrace.conf\n\n", "subsections": [] }, "AUTHOR": { "content": "Juan Cespedes \nPetr Machata \n\n", "subsections": [] }, "SEE ALSO": { "content": "ltrace.conf(5), strace(1), ptrace(2)\n\n\n\nJanuary 2013 LTRACE(1)", "subsections": [] } } } }