Syscalls used

1. Getline()

ssize_t getline(char **lineptr, size_t *n, FILE *stream);

Description: Reads a line of text from a stream. It can be a file, a pipe or standard input

2. Fork()

pid_t fork(void);

Description: Creates a child process by duplicating the calling process.

3. Wait()

pid_t wait(int *wstatus);

Description: Causes the current processes to wait until of its child process terminates.

4. Execve()

int execve(const char *pathname, char *const argv[], char *const envp[]);

Description: Execute a new programmed referred to by the pathname variable. Here, argv[] is an array of strings, envp[] .......................

5. Strtok()

char *stork(chat *str, const char *delim);

Description: Breaks a string into a sequence of tokens(a sequence of characters seperated by a delim)

6. Getenv()

char *getenv(const char *name);

Description: Searches the environment list to find the environment variable name.

7. Stat()

int stat(const char *pathname, struct stat *statbuf);

Description: Returns the information about the file in the buffer pointed to by the statbuf variable.

8. Access()

int access(const char *pathname, int mode);

Description: Checks whether the file pathname can be accessed. Mode:

• F_OK: If file exits
• R_OK: If file exists and grants read permissions
• W_OK: If file exists and grants write permissions
• X_OK: If file exists and grants execute permissions

9. Strdup()

char *strdup(const char *s);

Description: Returns a pointer to a new string which is a duplicate of the string s.

10. Isatty()

int isatty(int fd);

Description: Checks if the file is opened in interactive or non-interactive mode using the file descriptor.

Misc

1. size_t, ssize_t

• Count of bytes. Result of sizeof operator.
• Included in <string.h>, <sys/types.h>, ..., etc.

2. pid_t

• Process/User/Group identifier
• <sys/types.h>

3. perror()

• print a system error message
• <stdio.h>