Profile Management

A user profile is a visual display of personal data associated with a specific user, or a customized desktop environment. A profile refers therefore to the explicit digital representation of a person's identity. A user profile can also be considered as the computer representation of a user model.

/etc/profile                 -           it contains system void variables, if you do any modification in this file it will effect to the administrator and local user profiles.

~/.bash_profile         -           it contains user specific variables, if you do any modification in this file it will effect to that particular account only.

/etc/bashrc                 -           it contains system void alias variables

~/.bashrc                   -           it contains user specific alias variables

.bash_history           -           it contains all executed commands history

Commands:

# alias                        -           it will show the aliases 

[root@sankar ~]# alias
alias cp='cp -i'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
[root@sankar ~]#

# unalias <alias name>     -           it will remove mentioned alias

Note: you can always define an alias using /etc/bashrc OR .bashrc files

File Permissions:

Permission	Value	Number
Read	r	4
Write	w	2
Execute	x	1

Default permissions when you create a file or directory

File Permissions
File	644
Directory	755

File and Directory Permissions

In above image explained about file permissions

Commands to Change file/directory permissions

Symbolic permissions

u          -           user/owner

g          -           Group

o          -           Others

w         -           Write

x          -           Execute

+          -           Allow

-           -           deny

# chmod [options] <mode/permissions> <file/directory> - to change permissions file/folder

            Example: chmod 744 file1

# chmod u+rwx file or directory : in case of user only

                        # chmod ug+rwx file or directoty : in case of user and group

                        # chmod u+w,g+r,o+x directory/file

                        # chmod u+rw,g+rw directory/file

                        # chmod u-r, g-w,o-rw directory/file

                        # chmod ugo+rwx file/directory

                        # chmod ugo-rwx file/directory

# chown [options] <new owner> <file/directory> - to change ownership of file/folder

            Example: chown user2 file1

                            chown user1:group1 file2

# chgrp [options] <new group> <file/directory> - to change group of file/folder

            Example: chgrp gorup2 file2