Example output
The following is the first few lines of an invocation of xterm . It shows ltrace displaying calls to a variety of libraries, including the C standard library (malloc, strlen), POSIX libraries (getuid), X Toolkit Intrinsics (XtOpenApplication), and the X11 inter-client communication library (IceAddConnectionWatch). A call's return value is shown after the = symbol.
[pid11783]__libc_start_main(0x407420,1,0x7fff75b6aad8,0x443cc0,0x443d50<unfinished...>[pid11783]geteuid()=1000[pid11783]getegid()=1000[pid11783]getuid()=1000[pid11783]getgid()=1000[pid11783]setuid(1000)=0[pid11783]malloc(91)=0x00cf8010[pid11783]XtSetLanguageProc(0,0,0,0x7f968c9a3740,1)=0x7f968bc16220[pid11783]ioctl(0,21505,0x7fff75b6a960)=0[pid11783]XtSetErrorHandler(0x42bbb0,0x44f99c,0x669f80,146,0x7fff75b6a72c)=0[pid11783]XtOpenApplication(0x670260,0x44f99c,0x669f80,146,0x7fff75b6a72c)=0xd219a0[pid11783]IceAddConnectionWatch(0x42adc0,0,0,0x7f968c9a3748,0<unfinished...>[pid11783]IceConnectionNumber(0xd17ec0,0,1,0xcfb138,0xd17c00)=4[pid11783]<...IceAddConnectionWatchresumed>)=1[pid11783]XtSetErrorHandler(0,0,1,0xcfb138,0xd17c00)=0[pid11783]XtGetApplicationResources(0xd219a0,0x6701c0,0x66b220,34,0)=0[pid11783]strlen("off")=3
The GNU Debugger (GDB) is a portable debugger that runs on many Unix-like systems and works for many programming languages, including Ada, Assembly, C, C++, D, Fortran, Haskell, Go, Objective-C, OpenCL C, Modula-2, Pascal, Rust, and partially others.
DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on 16 July 2003.
In computing, particularly in the context of the Unix operating system and its workalikes, fork is an operation whereby a process creates a copy of itself. It is an interface which is required for compliance with the POSIX and Single UNIX Specification standards. It is usually implemented as a C standard library wrapper to the fork, clone, or other system calls of the kernel. Fork is the primary method of process creation on Unix-like operating systems.
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. It is a wrapper around the system calls of the Linux kernel for application use. Despite its name, it now also directly supports C++. It was started in the 1980s by the Free Software Foundation (FSF) for the GNU operating system.
The C standard library or libc is the standard library for the C programming language, as specified in the ISO C standard. Starting from the original ANSI C standard, it was developed at the same time as the C library POSIX specification, which is a superset of it. Since ANSI C was adopted by the International Organization for Standardization, the C standard library is also called the ISO C library.
C dynamic memory allocation refers to performing manual memory management for dynamic memory allocation in the C programming language via a group of functions in the C standard library, namely malloc, realloc, calloc, aligned_alloc and free.
XNU is the computer operating system (OS) kernel developed at Apple Inc. since December 1996 for use in the Mac OS X operating system and released as free and open-source software as part of the Darwin OS, which in addition to macOS is also the basis for the Apple TV Software, iOS, iPadOS, watchOS, visionOS, and tvOS OSes.
Address space layout randomization (ASLR) is a computer security technique involved in preventing exploitation of memory corruption vulnerabilities. In order to prevent an attacker from reliably redirecting code execution to, for example, a particular exploited function in memory, ASLR randomly arranges the address space positions of key data areas of a process, including the base of the executable and the positions of the stack, heap and libraries.
Signals are standardized messages sent to a running program to trigger specific behavior, such as quitting or error handling. They are a limited form of inter-process communication (IPC), typically used in Unix, Unix-like, and other POSIX-compliant operating systems.
DTrace is a comprehensive dynamic tracing framework originally created by Sun Microsystems for troubleshooting kernel and application problems on production systems in real time. Originally developed for Solaris, it has since been released under the free Common Development and Distribution License (CDDL) in OpenSolaris and its descendant illumos, and has been ported to several other Unix-like systems.
The proc filesystem (procfs) is a special filesystem in Unix-like operating systems that presents information about processes and other system information in a hierarchical file-like structure, providing a more convenient and standardized method for dynamically accessing process data held in the kernel than traditional tracing methods or direct access to kernel memory. Typically, it is mapped to a mount point named /proc at boot time. The proc file system acts as an interface to internal data structures about running processes in the kernel. In Linux, it can also be used to obtain information about the kernel and to change certain kernel parameters at runtime (sysctl).
Xlib is an X Window System protocol client library written in the C programming language. It contains functions for interacting with an X server. These functions allow programmers to write programs without knowing the details of the X protocol.
strace is a diagnostic, debugging and instructional userspace utility for Linux. It is used to monitor and tamper with interactions between processes and the Linux kernel, which include system calls, signal deliveries, and changes of process state. The operation of strace is made possible by the kernel feature known as ptrace.
A hybrid kernel is an operating system kernel architecture that attempts to combine aspects and benefits of microkernel and monolithic kernel architectures used in operating systems.
In computer science, the event loop is a programming construct or design pattern that waits for and dispatches events or messages in a program. The event loop works by making a request to some internal or external "event provider", then calls the relevant event handler. The event loop is also sometimes referred to as the message dispatcher, message loop, message pump, or run loop.
GNU variants are operating systems based upon the GNU operating system. According to the GNU project and others, these also include most operating systems using the Linux kernel and a few others using BSD-based kernels.
A Unix-like operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell. Although there are general philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like.
LTTng is a system software package for correlated tracing of the Linux kernel, applications and libraries. The project was originated by Mathieu Desnoyers with an initial release in 2005. Its predecessor is the Linux Trace Toolkit.
ptrace is a system call found in Unix and several Unix-like operating systems. By using ptrace one process can control another, enabling the controller to inspect and manipulate the internal state of its target. ptrace is used by debuggers and other code-analysis tools, mostly as aids to software development.
musl is a C standard library intended for operating systems based on the Linux kernel, released under the MIT License. It was developed by Rich Felker to write a clean, efficient, and standards-conformant libc implementation.
