LPIC-1 Exam 102 Topic 105: Shells and Shell Scripting

Customize and Use the Shell Environment

• Set environment variables at login or when spawning a new shell, e.g., PATH.
• Write Bash functions for frequently used sequences of commands.
• Maintain skeleton directories for new user accounts.
• Set command search path with the proper directory.

Environment Variables

• /etc/bash.bashrc and /etc/profile are used to set environment variables.
• env, export, set, and unset are used to manipulate environment variables.
• ~/.bash_profile, ~/.bash_login, ~/.profile, ~/.bashrc, and ~/.bash_logout are used to set environment variables for individual users.

Bash Commands

• source command is used to load a file into the current shell.
• function command is used to define a function.
• alias command is used to define an alias.

Setting Language and Working Directory

• export LANG=es_ES.UTF-8 sets the language of the current shell to Spanish UTF-8.
• pwd command prints the name of the current working directory.

Setting and Using Variables

• export PATH=$PATH:/home/carol/scripts sets the PATH environment variable to include a new directory.
• my_path=$PATH sets the value of my_path to the value of PATH.
• mammal=gnu sets a local variable mammal to the value gnu.
• var_sub="The value of mammal is $mammal" sets a local variable var_sub using variable substitution.

Creating and Searching Environment Variables

• export mammal=gnu turns a local variable into an environment variable.
• set | grep mammal and env | grep mammal are used to search for an environment variable.

Creating and Managing Directories

• mkdir ~/bin creates a new directory named bin in the home directory.
• export PATH=$PATH:~/bin adds the ~/bin directory to the PATH environment variable.

Adding to ~/.profile

• if [ -d ~/bin ]; then export PATH=$PATH:~/bin; fi is used to add the ~/bin directory to the PATH environment variable in the ~/.profile file.