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109 lines
3.8 KiB
109 lines
3.8 KiB
#!/bin/sh |
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# This spell will teach you how to work with environment variables in POSIX-compliant Bash |
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# This spell will teach you about environment variables, which are variables that are accessible to all processes running in the operating system. They store information such as system paths, user preferences, and other settings. |
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# Limitations on naming conventions vary by operating system, but in general, they can only contain alphanumeric characters and underscores, and have a maximum length of around 1024 characters. They cannot be aliased, but they can be exported and referenced in the .bashrc file. |
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echo "To cast the spell, please use the command: ./25_env.sh" |
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# Setting an environment variable |
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export MY_ENV_VAR="This is my environment variable" |
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echo "Environment variable MY_ENV_VAR is set to $MY_ENV_VAR" |
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# Checking if an environment variable is set |
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if [ -z "$MY_ENV_VAR" ]; then |
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echo "MY_ENV_VAR is not set" |
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else |
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echo "MY_ENV_VAR is set to $MY_ENV_VAR" |
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fi |
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# Exporting a variable in .bashrc |
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echo "export MY_ENV_VAR_IN_BASHRC=This variable is set in .bashrc" >> ~/.bashrc |
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# Loading .bashrc |
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source ~/.bashrc |
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echo "MY_ENV_VAR_IN_BASHRC is set to $MY_ENV_VAR_IN_BASHRC" |
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echo "Spell cast successfully" |
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#!/bin/sh |
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# This spell will teach you about environment variables and exporting in POSIX-compliant Bash |
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# Environment variables are variables that contain information about the environment in which a process runs. They can be used to set various options and make certain information available to processes. |
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# The limitations on names of environment variables are that they can only contain letters, numbers, and underscores, and the maximum length is determined by the system's limit on the length of environment variable strings. Environment variables cannot be aliased. |
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# Setting an environment variable |
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export MY_ENV_VAR="This is my environment variable" |
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echo "MY_ENV_VAR is set to: $MY_ENV_VAR" |
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# Accessing an environment variable |
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echo "The value of MY_ENV_VAR is: $MY_ENV_VAR" |
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# Exporting an environment variable in .bashrc |
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echo "export MY_ENV_VAR=\"This is my environment variable\"" >> ~/.bashrc |
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# Accessing an exported environment variable in a new terminal session |
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echo "The value of MY_ENV_VAR is: $MY_ENV_VAR" |
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echo "Spell cast successfully" |
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#!/bin/sh |
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# This spell will teach you the basics of environment variables in POSIX-compliant Bash |
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# To study the code of the examples, please use the command: cat 25_env.sh |
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echo "Welcome to the land of magic, where we will be learning about environment variables" |
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# Setting an environment variable |
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export MY_VAR="Dragon's breath" |
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echo "The variable MY_VAR has been set to $MY_VAR" |
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# Listing all environment variables |
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echo "All the current environment variables are:" |
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printenv |
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# Unsetting an environment variable |
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unset MY_VAR |
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echo "The variable MY_VAR has been unset" |
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# Checking if a variable is set |
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if [ -z "$MY_VAR" ]; then |
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echo "MY_VAR is unset" |
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else |
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echo "MY_VAR is set" |
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fi |
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# Using an environment variable in a command |
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export FILE_LOCATION="/usr/local/spells" |
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ls $FILE_LOCATION |
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echo "Spell cast successfully" |
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#!/bin/sh |
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# This spell will teach you the basics of working with environment variables in POSIX-compliant Bash |
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# Listing all environment variables |
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echo "The current environment variables are:" |
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printenv |
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# Setting an environment variable |
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export MY_VAR="Dragon's breath potion" |
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# Checking if a variable is set |
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if [ -z "$MY_VAR" ]; then |
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echo "MY_VAR is not set" |
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else |
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echo "MY_VAR is set to $MY_VAR" |
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fi |
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# Using an environment variable in a command |
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echo "The ingredients of the $MY_VAR are:" |
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cat potion_recipe.txt |
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# Unsetting an environment variable |
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unset MY_VAR |
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# Special predefined environment variables |
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echo "The current working directory is $PWD" |
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echo "The current user is $USER" |
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echo "The current shell is $SHELL" |
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echo "Spell cast successfully" |