Difference between revisions of "c/program/system"
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===Return value=== | ===Return value=== | ||
| − | Implementation-defined value. If {{tt|command}} is | + | Implementation-defined value. If {{tt|command}} is a null pointer, returns a nonzero value if and only if the command processor exists. |
===Notes=== | ===Notes=== | ||
Revision as of 00:52, 5 July 2017
| 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 host environment has a command processor and returns a nonzero value if and only if the command processor exists.
Contents |
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
Related POSIX function popen makes the output generated by command available to the caller.
Example
In this example there is a system call of the unix command ls -l >test.txt:
Run this code
#include <stdlib.h> int main(void) { system("ls -l >test.txt"); return 0; }
References
- 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
See also
| C++ documentation for system
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