system
| Defined in header <stdlib.h>
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| int system( const char *command ); |
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Calls the host environment's command processor 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.
Contents |
[edit] 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 |
[edit] Return value
Implementation-defined value. If command is a null pointer, returns a nonzero value if and only if the command processor exists.
[edit] 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.
[edit] Example
In this example there is a system call of the unix command date +%A and a system call to (possibly installed) gcc compiler with command-line argument (--version):
#include <stdlib.h> int main(void) { system("date +%A"); system("gcc --version"); }
Possible output:
Wednesday gcc (GCC) 11.2.0 ...
[edit] References
- C17 standard (ISO/IEC 9899:2018):
- 7.22.4.8 The system function (p: 257)
- C11 standard (ISO/IEC 9899:2011):
- 7.22.4.8 The system function (p: 353-354)
- C99 standard (ISO/IEC 9899:1999):
- 7.20.4.6 The system function (p: 317)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.10.4.5 The system function
[edit] See also
| C++ documentation for system
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