Shell Basic Command File Management - wwangdev/wwangdev.github.io GitHub Wiki

#Shell Basic Command -- File Management

Need to know

  • Linux use '/' instead of '' to for directories.

  • Linux File System Hierarchy: "man hier" for more details

    • /bin
    • /boot
    • /dev
    • /etc
    • /home
    • /lib
    • /lib64
    • /mnt
    • /opt
    • /proc
    • /root
    • /sbin
    • /tmp
    • /usr
    • /var
    • /lost+found

  • Mode bits: owner(u), group(g), and others(o); each has three bits -- read(r), write(w), and execute(x).

  • For folders: x -- entrance, r -- list files, w -- rm/mv/touch files.

  • File Types:

    • -: regular file
    • d: directory
    • b: block file
    • c: character device file
    • p: named pipe file or just a pipe file
    • l: symbolic link file
    • s: socket file

Share Files

Make group example

  • $ sudo groupadd workgroup add a group named workgroup
  • $ sudo useradd -G workgroup xxl add user xxl to workgroup
  • $ sudo passwd xxl set password for xxl
  • $ sudo mkdir work makedir with owner/group root
  • $ sudo chgrp workgroup work change group of work to workgroup
  • $ sudo chmod g+rwx work add group mod of work of rwx
  • $ sudo chmod o-rwx work remove other mod of work of rwx
  • $ sudo chown ww work change owner of work to ww
  • $ touch test make a file
  • $ su xxl switch to user: xxl
  • $ rm test delete file test

If want to add an existing user to a group, use:

sudo usermod -a -G workgroup xxl: -a:append.

Directory and File Manipulation

New

  • mkdir: make directory. -p: make parents directory if needed.
  • touch: make empty file or modify the establish time and date of a file.

Move

  • mv: move. -i: prompt when overwrite, -b: add "~" to old files when conflict.
  • mv: rename.

Copy

  • cp: copy. -i: prompt when overwrite, -b: add "~" to old files when conflict, -r: recursive, with folder.

Remove

  • rmdir: remove a directory
  • rm: remove file/directory. -i: prompt, -f: no prompt even with read-only file, -r: recursive.

Change owner and group

  • chown: sudo chown xxl:workgroup work change work's owner to xxl and workgroup to workgroup.
  • chown :nogroup keep owner and change group to nogroup
  • chown -R: recursive.
  • chgrp: chgrp XXX is the same as chown :XXX.

Change mode

  • chmod: chmod [ugoa][+-=][rwx].
  • chmod o=u XXX mod other as user mode bits
  • Only owner and root can modify mode bits.
  • chmod 751 XXX rwxr-x--x

Link

  • ln: ln-s Target Link_name link a Link_name to Target
  • ln -s: soft link; no "-s": hard link. Use -s!

Redirect

  • >: write to.
  • >>: append to.
  • <<: << XX : read until XX.

Pipe

  • |: ls | grep ay ls result as input of grep ay