CSCI 347 Test 2 Review: Files and Directories
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CSCI 347 Test 2 Review: Files and Directories

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Questions and Answers

Which system call is used to create a new process?

  • wait
  • fork (correct)
  • exec
  • pid

    • What is the purpose of the umask access?

  • To create hard links between files
  • To rename a file
  • To set default permissions for new files and directories (correct)
  • To change the ownership of a file

    • What does the /etc/passwd file contain?

  • A list of system users (correct)
  • A list of system processes
  • A list of system files
  • A list of system groups

    • What is the purpose of the setbuf function?

    <p>To set the buffering mode</p> Signup and view all the answers

    What is a zombie process?

    <p>A process that has terminated but its parent has not waited for it</p> Signup and view all the answers

    What is the purpose of the readdir function?

    <p>To read from a directory</p> Signup and view all the answers

    What is the purpose of the inode in a UNIX file system?

    <p>To store the file name and its associated metadata</p> Signup and view all the answers

    What is the effect of setting the Set UID bit on a file?

    <p>The file is executed with the owner's permissions</p> Signup and view all the answers

    What is the purpose of the dirname function in the Standard I/O Library?

    <p>To get the directory name from a file path</p> Signup and view all the answers

    What is the significance of the /etc/group file?

    <p>It stores information about system groups</p> Signup and view all the answers

    What is the purpose of the gettimeofday function?

    <p>To get the current system time</p> Signup and view all the answers

    What is the result of calling the fork function?

    <p>A new process is created and the parent process continues</p> Signup and view all the answers

    What is the purpose of the waitpid function?

    <p>To wait for a child process to terminate</p> Signup and view all the answers

    What is the purpose of the pipe function in interprocess communication?

    <p>To establish a communication channel between processes</p> Signup and view all the answers

    What is the purpose of the chmod function?

    <p>To change the file permissions</p> Signup and view all the answers

    What is the significance of the utimes function?

    <p>It sets the file modification time</p> Signup and view all the answers

    Study Notes

    Files and Directories

    • A UNIX file system consists of disk partitions
    • File types and directory entries are stored as (name, inode-number) pairs
    • Links can be hard (inode: data stored and access to file data via direct and indirect blocks) or symbolic
    • Ownership of a file can be viewed using stat, fstat, and lstat commands, with permissions for user/group/other
    • Set UID and Set GID bits can be set, and access control can be modified using umask, chmod, and fchmod commands
    • Files can be managed using chown, fchown, link, unlink, rename, and utimes commands
    • Directories can be managed using mkdir, rmdir, chdir, and fchdir commands
    • File descriptors can be manipulated using opendir, closedir, readdir, telldir, seekdir, and rewinddir commands

    Standard I/O Library

    • Standard input, output, and error streams (stdin, stdout, stderr) can be buffered, line-buffered, or unbuffered
    • Files can be opened using fopen, freopen, and fdopen commands
    • Buffering modes can be set using setbuf and setvbuf commands
    • File input/output can be performed using fgetc, ferror, feof, clearerr, and ungetc commands
    • Formatted input/output can be performed using fgets, fputs, and printf commands
    • Binary input/output can be performed using fread, fwrite, ftell, fseek, fgetpos, and fsetpos commands

    System Information

    • /etc/passwd and /etc/group files store user and group information
    • User and group information can be retrieved using getpwuid, getpwnam, getpwent, setpwent, and endpwent commands
    • Supplementary Group IDs can be used to add groups to a user
    • /etc directory stores system information
    • uname(1) and uname(3) commands provide system information
    • Time-related functions include time, ctime, strftime, gettimeofday, and others
    • Time zone issues can be handled using certain functions

    Process Control

    • Process ID (pid) and group ID (gid) can be used to manage processes
    • fork function creates a new process, and exit function terminates a process
    • wait and waitpid system calls can be used to wait for a process to terminate
    • WIFEXITED() and WEXITSTATUS() macros provide exit status information
    • Zombie processes can be terminated using wait, waitpid, wait3, and wait4 commands

    Pipes

    • Pipes enable interprocess communication
    • Kernel pipe, pipe(2) system call creates a pipe
    • Pipes have read and write ends
    • Termination conditions include EOF on read and SIGPIPE on write
    • One-way communication can be achieved from child to parent, or parent to child using pipes
    • popen(3) and pclose(3) commands can be used to create and manage pipes
    • micro shell concepts include exit values, expansion, environment variables, builtin commands, shell scripts, and script arguments

    Files and Directories

    • A UNIX file system consists of disk partitions
    • File types and directory entries are stored as (name, inode-number) pairs
    • Links can be hard (inode: data stored and access to file data via direct and indirect blocks) or symbolic
    • Ownership of a file can be viewed using stat, fstat, and lstat commands, with permissions for user/group/other
    • Set UID and Set GID bits can be set, and access control can be modified using umask, chmod, and fchmod commands
    • Files can be managed using chown, fchown, link, unlink, rename, and utimes commands
    • Directories can be managed using mkdir, rmdir, chdir, and fchdir commands
    • File descriptors can be manipulated using opendir, closedir, readdir, telldir, seekdir, and rewinddir commands

    Standard I/O Library

    • Standard input, output, and error streams (stdin, stdout, stderr) can be buffered, line-buffered, or unbuffered
    • Files can be opened using fopen, freopen, and fdopen commands
    • Buffering modes can be set using setbuf and setvbuf commands
    • File input/output can be performed using fgetc, ferror, feof, clearerr, and ungetc commands
    • Formatted input/output can be performed using fgets, fputs, and printf commands
    • Binary input/output can be performed using fread, fwrite, ftell, fseek, fgetpos, and fsetpos commands

    System Information

    • /etc/passwd and /etc/group files store user and group information
    • User and group information can be retrieved using getpwuid, getpwnam, getpwent, setpwent, and endpwent commands
    • Supplementary Group IDs can be used to add groups to a user
    • /etc directory stores system information
    • uname(1) and uname(3) commands provide system information
    • Time-related functions include time, ctime, strftime, gettimeofday, and others
    • Time zone issues can be handled using certain functions

    Process Control

    • Process ID (pid) and group ID (gid) can be used to manage processes
    • fork function creates a new process, and exit function terminates a process
    • wait and waitpid system calls can be used to wait for a process to terminate
    • WIFEXITED() and WEXITSTATUS() macros provide exit status information
    • Zombie processes can be terminated using wait, waitpid, wait3, and wait4 commands

    Pipes

    • Pipes enable interprocess communication
    • Kernel pipe, pipe(2) system call creates a pipe
    • Pipes have read and write ends
    • Termination conditions include EOF on read and SIGPIPE on write
    • One-way communication can be achieved from child to parent, or parent to child using pipes
    • popen(3) and pclose(3) commands can be used to create and manage pipes
    • micro shell concepts include exit values, expansion, environment variables, builtin commands, shell scripts, and script arguments

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    Description

    Review of chapters 4, 5, 6, 8, and 15 for CSCI 347 Test 2, covering topics like files and directories, UNIX file system, and disk partitions.

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