Execute a command using the shell.
Syntax |
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#include <stdlib.h>
int system(const char *command);
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Parameters |
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- command
is a string giving the command line for the command you want to execute using the shell (MPE/iX Shell).
Return Values |
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If command is NULL, system() returns -1.
If command is not NULL, system() returns the exit status of the sh command that executes command. If sh cannot be invoked to execute the command, the return value of system() is the value that would be received if sh terminated with exit(127).
If system() cannot fork() a child process, it returns -1 and sets errno to an appropriate value. It uses the same errno values used by fork() for its possible failures.
Description |
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system() executes the command specified by command. It does this as if it spawns a child process with fork(), then the child process invokes the shell sh with
execl(shellpath, "sh", "-c", command, NULL);
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where shellpath is the pathname of the file that contains
the MPE/iX Shell.
system() ignores the SIGINT and SIGQUIT signals while waiting for the command to terminate. It also blocks the SIGCHLD signal. After the command terminates, the calling process can examine the return value from system() to determine if any of these signals should be handled.
Implementation Considerations |
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None.
Errors |
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None.
See Also |
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sh(1)
