std::system

 

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General utilities Date and time Function objects Formatting library (C++20) bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator> rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)    cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17)

 

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abort exit quick_exit (C++11) _Exit (C++11)	atexit at_quick_exit (C++11) EXIT_SUCCESSEXIT_FAILURE
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unreachable (C++23)
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system	getenv
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SIGABRTSIGFPESIGILL	SIGINTSIGSEGVSIGTERM
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setjmp
longjmp
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jmp_buf

 

Defined in header <cstdlib>
int system( const char* command );

Calls the host environment's command processor (e.g. /bin/sh, cmd.exe, command.com) with the parameter command. Returns an implementation-defined value (usually the value that the invoked program returns).

If command is a null pointer, checks if the host environment has a command processor and returns a nonzero value if and only if the command processor exists.

Parameters

command

-

character string identifying the command to be run in the command processor. If a null pointer is given, command processor is checked for existence

Return value

Implementation-defined value. If command is a null pointer, returns a nonzero value if and only if the command processor exists.

Notes

On POSIX systems, the return value can be decomposed using WEXITSTATUS and WSTOPSIG

The related POSIX function popen makes the output generated by command available to the caller.

An explicit flush of std::cout is also necessary before a call to std::system, if the spawned process performs any screen I/O.

Example

Run this code

#include <cstdlib>
#include <fstream>
#include <iostream>
 
int main()
{
    std::system("ls -l >test.txt"); // execute the UNIX command "ls -l >test.txt"
    std::cout << std::ifstream("test.txt").rdbuf();
}

Possible output:

total 16
-rwxr-xr-x 1 2001 2000 8859 Sep 30 20:52 a.out
-rw-rw-rw- 1 2001 2000  161 Sep 30 20:52 main.cpp
-rw-r--r-- 1 2001 2000    0 Sep 30 20:52 test.txt