process.h

process.h

In C and C++ programming, process.h is a header file primarily associated with older or system-specific compilers, notably Borland compilers. It provides declarations for functions related to process management, such as creating, terminating, and executing other programs.

Historically, process.h was a common header on DOS and Windows systems using Borland's C/C++ compilers. However, its functionality is largely superseded by standard POSIX functions (defined in unistd.h, which is typically available on Unix-like systems) and the standard C library (stdlib.h in C, or the C++ standard library). Therefore, process.h is considered non-standard and its use is generally discouraged in modern, portable code.

The functions typically declared in process.h (though specifics can vary by compiler) include:

• spawnl, spawnle, spawnlp, spawnlpe, spawnv, spawnve, spawnvp, spawnvpe: These functions execute a new child process. They differ in how they accept arguments (as a list of individual arguments or an array of arguments), whether they search the directories listed in the PATH environment variable, and whether they accept an explicit environment for the new process. These are essentially variants of the exec family of functions commonly found in POSIX systems.

• execl, execle, execlp, execv, execve, execvp: Replace the current process image with a new process image. Similar to spawn, but exec functions will replace the current process rather than spawning a new one.

• system: Executes a command specified as a string using the system's command interpreter. This function is also available through the standard library (stdlib.h).

• _exit: Terminates the calling process immediately. This function bypasses normal exit processing (e.g., flushing buffers, calling exit handlers). It is also part of the standard library's exit functionalities.

Because process.h is non-standard, its availability and specific function declarations are dependent on the compiler and operating system. Portable programs should rely on standard alternatives like unistd.h (for Unix-like systems) or the functions in stdlib.h which have cross-platform implementations (e.g. system(), exit()). When writing cross-platform code, use conditional compilation (e.g., #ifdef _WIN32, #ifdef __linux__) to handle platform-specific differences and include the appropriate headers for each target environment. Using POSIX compatible functions like fork(), execve(), and wait() where possible promotes code portability.