In the following C function, we can launch a command and capture its output and store in a 2 dimensional char array. The function returns the number of the lines of the output. Each line is ended with the new line carriage “\n”.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #define LINE_MAX_BUFFER_SIZE 255 int runExternalCommand(char *cmd, char lines[][LINE_MAX_BUFFER_SIZE]) { FILE *fp; char path[LINE_MAX_BUFFER_SIZE]; /* Open the command for reading. */ fp = popen(cmd, "r"); if (fp == NULL) { return -1; } int cnt = 0; while (fgets(path, sizeof(path), fp) != NULL) { strcpy(lines[cnt++], path); } pclose(fp); return cnt; } |
#define LINE_MAX_BUFFER_SIZE 255
int runExternalCommand(char *cmd, char lines[][LINE_MAX_BUFFER_SIZE]) {
FILE *fp;
char path[LINE_MAX_BUFFER_SIZE];
/* Open the command for reading. */
fp = popen(cmd, "r");
if (fp == NULL) {
return -1;
}
int cnt = 0;
while (fgets(path, sizeof(path), fp) != NULL) {
strcpy(lines[cnt++], path);
}
pclose(fp);
return cnt;
}In order to use this function, you would need to allocate the **char array in advance. In C, you would usually allocate and deallocate the array in the caller. One example:
1 2 3 4 5 6 7 8 | int main() { char output[100][LINE_MAX_BUFFER_SIZE]; int a = runExternalCommand("ls", output); for (int i = 0; i < a; ++ i) { printf("%s", output[i]); } return 0; } |
int main() {
char output[100][LINE_MAX_BUFFER_SIZE];
int a = runExternalCommand("ls", output);
for (int i = 0; i < a; ++ i) {
printf("%s", output[i]);
}
return 0;
}–EOF (The Ultimate Computing & Technology Blog) —
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