I am trying to cat some file into another new files, but to my surprise its not working.
Able to do the same if i execute the same command on terminal, but through system call, it not working.
I just need a new set of eyes to look and point out the problem please
#include <string.h>
#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#define COMMON_COMMAND "cd %s;cat %s >> %s"
#define RPATH "/home/spark/R/"
#define R_CERTIFICATE_NOT_FOUND 2
#define RESULT_NOT_FOUND_FILE 5
#define DIR_CERTIFICATE_NOT_FOUND 6
#define RESULT_SUCCESS 0
#define BUFFER_SIZE 1000
/*Final file*/
#define COMMON_FILE "common_file_"
static int prepare_FinFiles(const char *rpath,char *common_file);
static int ReadFiles(const char *path,char *common_file);
int main()
{
char Finfile[BUFFER_SIZE] = {0};
char cmd[50] = {0};
struct timeval t1;
gettimeofday(&t1, NULL);
srand(t1.tv_usec);
prepare_FinFiles(RPATH,Finfile);
strcpy(cmd,"cat ");
strcat(cmd,Finfile);
printf(" cmd output ==> \n");
system(cmd);
return 0;
}
static int prepare_FinFiles(const char *rpath,char *common_file)
{
char command[BUFFER_SIZE] = {0};
char temp_files[BUFFER_SIZE] = {0};
int32_t count_no_files = 0;
char cmd[BUFFER_SIZE] = {0};
sprintf(common_file, "%s%d%s", "/home/spark/"COMMON_FILE,random(),".txt");
strcpy(cmd,"touch ");
strcat(cmd, common_file);
system(cmd);
if( ReadFiles(rpath,common_file) == RESULT_NOT_FOUND_FILE)
{
return R_CERTIFICATE_NOT_FOUND;
}
else if(retVal == DIR_CERTIFICATE_NOT_FOUND)
{
printf("dir not found\n");
return DIR_CERTIFICATE_NOT_FOUND;
}
else
{
printf("R read success\n");
char Finfile[BUFFER_SIZE] = {0};
char cmd[50] = {0};
strcpy(cmd,"cat ");
strcat(cmd,common_file);
printf("cmd : %s\n",cmd);
printf("The return value is: %d\n", WEXITSTATUS(system(cmd)));
}
}
static int32_t ReadFiles(const char *path,char *common_file)
{
DIR *dir = opendir(path);
struct dirent *dp;
char command[BUFFER_SIZE] = {0};
char temp_files[BUFFER_SIZE] = {0};
int count_no_files =0;
printf("Reading from %s path\n", path);
if(!dir)
{
return DIR_CERTIFICATE_NOT_FOUND;
}
else
{
while ((dp = readdir(dir)) != NULL)
{
if( strncmp(dp->d_name,".",strlen(".")) &&
strncmp(dp->d_name,"..",strlen(".."))
)
{
strncat(temp_files,dp->d_name,strlen(dp->d_name));
strncat(temp_files," ",strlen(" "));
count_no_files++;
}
}
if(count_no_files == 0)
{
return RESULT_NOT_FOUND_FILE;
}
else
{
memset(command,0,sizeof(command));
sprintf(command, COMMON_COMMAND, path,temp_files,common_file);
printf("command = %s\n", command);
return RESULT_SUCCESS;
}
}
}
output
Reading from /home/spark/R/ path
command = cd /home/spark/R/;cat file1.txt >> /home/spark/R/common_file_931058571.txt
R read success
cmd : cat /home/spark/R/common_file_931058571.txt
The return value is: 0
but through system call, it not working
Because you do not call system at all.
Your code contains 3 calls to system:
// in main
system(cmd); // cmd contains "cat /home/spark/common_file_<random>.txt"
// in prepare_FinFile
system(cmd); // cmd contains "touch /home/spark/common_file_<random>.txt"
...
printf("cmd : %s\n",cmd);
printf("The return value is: %d\n", WEXITSTATUS(system(cmd)));
// cmd contains "cat /home/spark/R/common_file_931058571.txt"
The command in question would be this:
printf("command = %s\n", command);
// command contains "cd /home/spark/R/;cat file1.txt >> /home/spark/R/common_file_931058571.txt"
return RESULT_SUCCESS;
But you never execute it. You just print it.
Related
Currently I am attempting to parse words from all text files in a directory (in this case it is safe to assume there will only be text files within the directory). It seems as though I am able to open the file within the threads function, however I am unable to grab the text within. No error messages are being presented but the printf within splitInput is not printing to the terminal.
Forgive my semantic work within the code, I am a fresh novice with C! Along with this there may be unused code within main as this will be part of a larger project. I appreciate the assistance in advance!
#include <stdlib.h>
#include <dirent.h>
#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include "queue.h"
void* splitInput(void *filename) {
printf("Thread %s Created\n", (char*)filename);
FILE *file;
int i = 0;
char *cp;
char *bp;
char line[255];
char *array[5000];
file = fopen((char*)filename, "r");
if(file == NULL) {
perror("Error opening file");
}
printf("Opened File %s\n", (char*)filename);
while(fgets(line, sizeof(line), file) != NULL) {
bp = line;
while(1) {
cp = strtok(bp, ",.!? \n");
bp = NULL;
if(cp == NULL) {
break;
}
array[i++] = cp;
printf("Check print - word %i:%s:\n", i-1, cp);
}
}
fclose(file);
return 0;
}
int main(int argc, char *argv[]) {
DIR* d;
struct dirent* e;
// grab our queueSize and threadCount
int queueSize = atoi(argv[2]);
int threadCount = atoi(argv[3]);
// var for creating a thread each file
int i = 0;
// open the dir
d = opendir(argv[1]);
printf("Queue Size: %d\n", queueSize);
printf("Thread Count: %d\n", threadCount);
// set our thread count now that we know how many files are in dir
pthread_t threads[threadCount];
// read through our directory
while((e = readdir(d)) != NULL) {
// make sure we aren't reading . and ..
if(strcmp(e->d_name, ".") == 0) {
continue;
}
if(strcmp(e->d_name, "..") == 0) {
continue;
}
printf("entered file %s\n", e->d_name);
char *filename = strdup(e->d_name);
if(i < threadCount) {
// create our threads
pthread_create(&threads[i], NULL, splitInput, filename);
}
// increment i
i++;
}
// join our existing threads
for(int j = 0; j < i; j++) {
pthread_join(threads[j], NULL);
}
return 0;
}
Current Output
device#user:~/os/testdir$ ./output ~/os/testdir/test 10 10 output
Queue Size: 10
Thread Count: 10
entered file test
Thread test Created
Opened File test
Found the answer, I was attempting to open a file outside my working directory which cannot be done without the full path. Changing the working directory to the parameter given solved the issue. This can be done in this case with chdir(argv[1])
Revised code below.
#include <stdlib.h>
#include <dirent.h>
#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include "queue.h"
void* splitInput(void *filename) {
printf("Thread %s Created\n", (char*)filename);
FILE *file;
int i = 0;
char *cp;
char *bp;
char line[255];
char *array[5000];
file = fopen((char*)filename, "r");
if(file == NULL) {
perror("Error opening file");
}
printf("Opened File %s\n", (char*)filename);
while(fgets(line, sizeof(line), file) != NULL) {
bp = line;
while(1) {
cp = strtok(bp, ",.!? \n");
bp = NULL;
if(cp == NULL) {
break;
}
array[i++] = cp;
printf("Check print - word %i:%s:\n", i-1, cp);
}
}
fclose(file);
return 0;
}
int main(int argc, char *argv[]) {
DIR* d;
struct dirent* e;
// grab our queueSize and threadCount
int queueSize = atoi(argv[2]);
int threadCount = atoi(argv[3]);
// var for creating a thread each file
int i = 0;
// open the dir
chdir(argv[1]);
d = opendir(argv[1]);
printf("Queue Size: %d\n", queueSize);
printf("Thread Count: %d\n", threadCount);
// set our thread count now that we know how many files are in dir
pthread_t threads[threadCount];
// read through our directory
while((e = readdir(d)) != NULL) {
// make sure we aren't reading . and ..
if(strcmp(e->d_name, ".") == 0) {
continue;
}
if(strcmp(e->d_name, "..") == 0) {
continue;
}
printf("entered file %s\n", e->d_name);
char *filename = strdup(e->d_name);
if(i < threadCount) {
// create our threads
pthread_create(&threads[i], NULL, splitInput, filename);
}
// increment i
i++;
}
// join our existing threads
for(int j = 0; j < i; j++) {
pthread_join(threads[j], NULL);
}
return 0;
}
SOURCE::
#include <stdio.h> // printf()
#include <stdlib.h> // exit()
#include <string.h> // string
#include <dirent.h> // microsoft base compiler. _chdir, _getcwd
#include <unistd.h> // unix base complier. getcwd, chdir
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#define FILE_SIZE 1024
#define MAX 255
#define ERROR (-1)
void cmd_mkdir(int argc, char *argv);
void cmd_ls()
{
char * cwd = (char *)malloc(sizeof(char) * 1024);
DIR * dir = NULL;
struct dirent * entry = NULL;
getcwd(cwd, 1024);
if( (dir = opendir(cwd)) == NULL)
{
printf("current directory error\n");
exit(1);
}
while( (entry = readdir(dir)) != NULL)
{
printf("%s\n", entry->d_name);
}
free(cwd);
closedir(dir);
}
void cmd_pwd() {
char buf[MAX];
getcwd(buf, MAX);
printf("%s\n", buf);
}
int main(int argc, char *argv[])
{
char cBuf[MAX];
char *arg;
while(1) {
printf(">> ");
arg = fgets(cBuf, MAX, stdin);
if(argc < 2){
// printf("1111\n"); -- check
if(strncmp(arg, "ls", 2) == 0)
cmd_ls();
else if(strncmp(arg, "pwd", 3) == 0)
cmd_pwd();
else if(strncmp(arg, "exit", 4) == 0)
break;
} // if END
else {
// printf("2222\n"); -- check
if(strcmp(arg, "mkdir") == 0){
if (argc != 2)
fprintf(stderr, "Usage : jmkdir dirname\n");
if(mkdir(argv[1], 0755))
perror("mkdir error");
}
}// else END
} // while END
} // main END
Desired result::
How to get two input values (mkdir, mini_maked) as parameters after executing ./minishell (executable file implementing the shell)
$ ./minishell
>> mkdir mini_maked
Currently implemented ls, pwd, exit can be implemented because it can be used without options, but a command that requires a "command filename" such as mkdir is not implemented.
If the program itself functions as mkdir, it is solved using the values of argc and argv.
However, since the ./myshell program itself implements the shell program, when you run the program and receive mkdir mini_maked as an input, you are having a hard time executing the command.
If we get two inputs (mkdir, mini_maked) after program execution, how do we get these as parameters?
Hello I'm working on a program that prints all the characters like a cat program by using the POSIX functions, the program has to get more than one file when it does it writes the characters of all files in the destination file.
For example;
mycat.exe x.txt y.txt z.txt dest.txt
means write all the characters from x.txt, y.txt and z.txt in order to the file destination dest.txt that it's created after we run the program.
If any file not exits the program will not exit it prints a report that
file not exists
If any error occur, you have to exit the program.
When I compile it it compiles without any error(I'm compiling it in Windows 10), but when i try to run it it shows an error.
This is how I compile it:
gcc -o mycp.exe mycp.c
This is how i run it:
mycp.exe x.txt y.txt z.txt dest.txt
This is the error:
copy: Bad file descriptor
This is the code inside the mycp.c:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#define BUFSIZE 1024
void exit_sys(const char* msg)
{
perror(msg);
exit(EXIT_FAILURE);
}
void exit_fail(const char* msg)
{
fprintf(stderr, "%s\n", msg);
exit(EXIT_FAILURE);
}
void remove_dest_file(int fd, char** argv, int i)
{
_close(fd);
unlink(argv[i]);
}
int copy_file(int fdd, int fds)
{
char buf[BUFSIZE];
int n;
while ((n = read(fds, buf, BUFSIZE)) > 0)
{
_write(fdd, buf, n);
}
if (n < 0)
{
return n;
}
return 0;
}
int main(int argc, char** argv)
{
int fds, fdd;
int n;
char buf[BUFSIZE];
int ch;
int flags;
int argcm1;
int i;
flags = _O_WRONLY | _O_CREAT;
if (argc < 2)
exit_fail("usage:mycp.exe file1.exe file2.exe file3.exe ... filen filedest.exe");
argcm1 = argc - 1;
if (!access(argv[argcm1], F_OK)) {
printf("The file %s exists. Do you want to overwrite?[y]\n", argv[argcm1]);
ch = getchar();
if (ch == 'y' || ch == 'Y')
flags |= _O_TRUNC;
else
exit(EXIT_SUCCESS);
}
if ((fdd = _open(argv[argcm1], flags, _S_IREAD | _S_IWRITE)) < 0)
{
exit_sys("open for destination");
}
for (i = 0; i < argcm1; ++i)
{
if (fds = _open(argv[i], _O_RDONLY) < 0)
{
remove_dest_file(fdd, argv, argcm1);
exit_sys("open");
}
if (copy_file(fds, fdd) < 0)
{
remove_dest_file(fdd, argv, argcm1);
exit_sys("copy");
}
_close(fds);
}
printf("Succes");
_close(fdd);
return 0;
}
I'm new to stack overflow so bear with me :)
I am trying to create a custom linux shell as a project.
Right now I want to make the default output going to a file instead of console when the user uses > symbol for example ls > filename.txt
But , the program crashes and a Bad address error pops yet it writes the command output to the file.
#include <sys/wait.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
typedef char* string;
int main (int argc,char** argv) {
int error = 0;
int posIn=0; int posOut=0; int appendMark=0;
string Output,Input;
while (1) {
error=0;
char progName[255];
printf("\nmysh3 > ");
if(fgets(progName,500,stdin)==NULL){return 0 ;}
char dir[1024];
string params[40];
string pch=progName;
int i=0;
while ((pch = strtok (pch," \n")) != NULL){
params[i]=pch;
if (strcmp(pch,"<")==0) { posIn = i;params[i]=NULL;i--;} // < is skipped and we put only the name of the command on the params array
if (strcmp(pch,">")==0) { posOut = i;params[i]=NULL;i--;} //output
if (strcmp(pch,">>")==0) {appendMark=1;params[i]=NULL;i--;}
i++;
pch = NULL;
}
params[i]=NULL;
if(strlen(progName)>255){
printf("The commands can't be over 255 characters\n");
return 0;
}
if (posOut) {
int out = open(params[posOut], O_CREAT|O_TRUNC|O_WRONLY, 0777);
params[posOut]=NULL;
if (out < 0) {
error = 1;
fprintf(stderr,"open error: %d [%s]\n",errno,strerror(errno));
exit(1); }
int k = dup2(out,1);
if (k<0) {
error = 1;
perror("Cannot redirect output");
}
close(out);
}
pid_t proccess1,waitpid;
int status;
proccess1 = fork();
if (proccess1<0) {perror("Out of memory"); } //Monos tropos na apotyxei h fork einai na mhn yparxei mnhmh
else if (proccess1==0) {
execvp(params[0],params);
if (!error) {perror("Unknown command");}
}
else {
waitpid=wait(&status);
if (waitpid==-1) {perror("ERROR: A NEW ZOMBIE IS BORN 3:)");return 0;}
}
}
return 0; }
need some advice on this one as im struggling abit and cannot figure it out.
i have a file that gets updated on a PC to indicate a system ran and what time it ran. i am writing a very simple linux console app (will eventually be a nagios plugin). that reads this file and responds depending on what it found within the file.
i am a total newbie to programming on Linux and using C so please be patient and if you would explain any answers it would really be appreciated.
basically i want to convert a char array containing 5 characters into an integer, however the 5th char in the array is always a letter. so technically all i want to-do is convert the first 4 chars in the array to a integer... how?? ive tried multiple ways with no success, my problem is that presently i do not have a good grasp of the language so have no real ideas on what it can and cannot do.
here is the source to my program.
basically the buf array will be holding a string taken from the file that will look something like this
3455Y (the number will be random but always 4 chars long).
Sorry for the poor formatting of the code, but i cannot get this stupid window for love nor money to format it correctly....
include <fcntl.h>
include <unistd.h>
include <stdio.h>
include <stdlib.h>
include <time.h>
include <string.h>
define COPYMODE 0644
int main(int argc, char *argv[])
{
int i, nRead, fd;
int source;
int STATE_OK = 0;
int STATE_WARNING = 1;
int STATE_CRITICAL = 2;
int STATE_UNKNOWN = 3;
int system_paused = 0;
char buf[5];
int testnumber;
if((fd = open(argv[1], O_RDONLY)) == -1)
{
printf("failed open : %s", argv[1]);
return STATE_UNKNOWN;
}
else
{
nRead = read(fd, buf, 5);
}
close(source);
if (buf[4] == 'P')
{
printf("Software Paused");
return STATE_WARNING;
}
else
{
return STATE_OK;
}
time_t ltime; /* calendar time */
struct tm *Tm;
ltime=time(NULL); /* get current cal time */
Tm=localtime(<ime);
int test;
test = Tm->tm_hour + Tm->tm_min;
printf("%d", test);
printf("%d", strtoi(buf));
}
You can use sscanf to do the job:
int num = 0;
sscanf(buf, "%4d", &num);
Then num should hold the number from the line in the file.
You can use atoi
atoi requires one char * argument and returns an int.
If the string is empty, or first character isn't a number or a minus sign, then atoi returns 0.If atoi encounters a non-number character, it returns the number formed up until that point
int num = atoi(buf);
if you want to convert the first four characters of a string to an integer do this:
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
uint8_t convertFirstFourChars(char * str, uint32_t *value){
char tmp[5] = {0};
strncpy((char *) tmp, str, 4);
*value = strtoul(tmp);
return errno;
}
then call / test this function like this
#include <stdint.h>
#include <stdio.h>
int main(int argc, char **argv){
char test1[5] = "1234A";
char test2[5] = "ABCDE";
uint32_t val = 0;
if(convertFirstFourChars((char *) test1, &val) == 0){
printf("conversion of %s succeeded, value = %ld\n", test1, val);
}
else{
printf("conversion of %s failed!\n", test1);
}
if(convertFirstFourChars((char *) test2, &val) == 0){
printf("conversion succeeded of %s, value = %ld\n", test2, val);
}
else{
printf("conversion of %s failed!\n", test2);
}
return 0;
}
FWIW, don't use atoi(...) because it converts any string to an integer regardless of its validity as a number. atoi("foo") === 0.
this is as much of your code as I was able to recover from the formatting:
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <time.h>
#define COPYMODE 0644
int main(int argc, char *argv[])
{
int i, nRead, fd;
int source;
int STATE_OK = 0;
int STATE_WARNING = 1;
int STATE_CRITICAL = 2;
int STATE_UNKNOWN = 3;
int system_paused = 0;
char buf[5];
int testnumber;
if((fd = open(argv[1], O_RDONLY)) == -1)
{
printf("failed open : %s", argv[1]);
return STATE_UNKNOWN;
}
else
{
nRead = read(fd, buf, 5);
}
close(source);
if (buf[4] == 'P')
{
printf("Software Paused");
return STATE_WARNING;
} else {
return STATE_OK;
}
time_t ltime; /* calendar time /
struct tm Tm;
ltime=time(NULL); / get current cal time */
Tm=localtime(<ime);
int test;
test = Tm->tm_hour + Tm->tm_min;
printf("%d", test);
printf("%d", strtoi(buf));
}
this is the version that does what you specified:
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <time.h>
#define COPYMODE 0644
int main(int argc, char *argv[])
{
int i, nRead, fd;
int source;
int STATE_OK = 0;
int STATE_WARNING = 1;
int STATE_CRITICAL = 2;
int STATE_UNKNOWN = 3;
int system_paused = 0;
char buf[5];
int testnumber;
if((fd = open(argv[1], O_RDONLY)) == -1)
{
printf("failed open : %s", argv[1]);
return STATE_UNKNOWN;
}
else
{
nRead = read(fd, buf, 5);
}
close(source);
if (buf[4] == 'P')
{
printf("Software Paused");
return STATE_WARNING;
}/* else {
return STATE_OK;
buf[4] = 0;
} */
time_t ltime; /* calendar time */
struct tm *Tm;
ltime=time(NULL); /* get current cal time */
Tm=localtime(<ime);
int test;
test = Tm->tm_hour + Tm->tm_min;
printf("%d\n", test);
printf("%d\n", atoi(buf));
}
The biggest problem with your code was the if statement with the returns in each branch, insuring that nothing after the if statement was ever executed.