Linux Cookbook 3

Files And Dirs

1. touch ---create a new, empty file

            vi filename is also ok

2. mkdir ---make directory

            mkdir -p ---to make all directories in the path

3. space in filename

            use '' or "" or /

            ls 'top secret'

            ls "top secret"

            ls top/ secret

4. cd ---change the current working dir

            1)cd ---To make your home directory the current working directory                       

            2)cd - ---Changing to the Last Directory You Visited

            3)pwd ---Getting the Name of the Current Directory

5. ls ---Listing Directories

            ls --color ---Listing Directories in Color

                    Some of the default color settings include displaying directory names in blue,

                    text files in white, executable files in green, and links in turquoise.

                    Many systems are set up to use this flag by default, so that using ls

                    with no options will list in color. If yours isn’t set up this way, and you’d like

                    it to be, you can always make ls a shell alias word for ls --color in your

                    .bashrc startup file

             ls -F ---Listing File Types

                    regular files are displayed as usual

                    / File is a directory.

                    * File is executable.

                    @ File is a symbolic link

                    | File is a fifo

                    = File is a socket

             ls -l(long) ---Listing File Attributes

                    The first character in this column specifies the file type;

                    the hyphen (-) is the default and means that the file is a regular file.

                    Directories are denoted by d

                    symbolic links are denoted by l

             ls --full-time ---show the full time and date

             ls -h ---human readable

             ls -a ---To list all files in the current directory, include Hidden Files

                    . ---a period character (.) means hidden file

             ls -A --- ls-a - . - ..

             ls -1 ---to list a directory in a single column

             ls -x ---To list the contents in columns printed horizontally

             ls -m ---to output files not in columns at all, but in a single horizontal line, separated by commas.

             ls -S ---To sort files by size, default is sorted alphabetically

             ls -t ---by time

             ls -X ---by extension

             ls -v ---so that file-2 will come between file-1 and file-10, very useful

             ls -r ---to reverse the order of the sorted output, can work with all the other sort options

             ls -U ---to turn off all sorting and output files in unsorted order—the order they appear on the disk.

             ks -R ---lists the contents of a directory recursively

6. cp ---Copying Files and Directories            

             cp -v ---to list files as they are copied

             cp -p ---to preserve all of the attributes of the original, whenever possible,

                      including its timestamp, owner, group, and permissions.

                      in every respect except for its name

             cp -a --- same as cp -p but recursively

             basename ---for i in ~/photographs/*; { cp -a $i/src /mnt`basename $i`; }

7. mv ---to move, or rename, a file or directory to a different location.

             Renaming a file is the same as moving it

             $ mv notes notes.old ---To rename the file notes to notes.old

8. rename ---

9. rm ---to delete a file and remove it from the system

             Removing a File with a Strange Name

                       1) use tab

                       2) use pattern, e.g rm -i ?cat

                       3) rm -- -cat ---To remove the file -cat from the current directory            

             Removing Files without Verification

                       $ yes | rm -R scrap

10. ln ---Linking a File to Another

             ln -s symbolic link

11. tree ---Listing Directory Tree Graphs

             tree -d ---only show dir                           

                   
permission

1. cat /etc/group ---To list the available groups on the system

2. groups ---Listing the Groups a User Belongs To

             groups marlow ---To list the group memberships of user marlow

3. members groupname ---to list the members of a particular group

             $ grep ^crew: /etc/group | cut -d : -f 4

4. $ chgrp bridge cruise ---To change the group ownership of file cruise to bridge

             -R ---recursively

5. ls -l         

             -rwxrw-r-- 1 captain crew 8,420 Jan 12 21:42 cruise

             The first character (“-”) is the file type; the next three characters (“rwx”)

             specify permissions for the user who owns the file; and the next three (“rw-”)

             specify permissions for all members of the group that owns the file except for

             the user who owns it. The last three characters in the column (“r--”) specify

             permissions for all other users on the system.            

6. chmod ---Changing the Permissions of a File

             u ---user

             g ---group

             o ---other users

             a ---all users

            

             + ---add

             - ---remove

             = ---Make these the only permissions the user has for this file

             r ---read

             w ---write

             x ---execute

             e.g

             chmod a+rw cruise ---Making a File Public

             chmod a+x myscript ---Making a File Executable

             chmod go= cruise ---To make the file cruise private from all users but yourself

             chmod go-w cruise ---Write-Protecting a File