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71 lines
2.2 KiB
71 lines
2.2 KiB
2 years ago
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## set-env-vars
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### Instructions
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Create a script `set-env-vars.sh`, which will allow you to set the following variables as environment variables and and print them all:
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- `MY_MESSAGE` which contains the string `"Hello World"`.
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- `MY_NUM` which contains the number `100`.
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- `MY_PI` which contains the number `3.142`.
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Expected output:
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```console
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$ printenv # The env variables present are just an example, yours will be different.
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SHELL=/bin/bash
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TERM=xterm
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USER=demouser
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LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca:...
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MAIL=/var/mail/demouser
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PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
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PWD=/home/demouser
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LANG=en_US.UTF-8
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SHLVL=1
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HOME=/home/demouser
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LOGNAME=demouser
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LESSOPEN=| /usr/bin/lesspipe %s
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LESSCLOSE=/usr/bin/lesspipe %s %s
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_=/usr/bin/printenv
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$ ./set-env-vars.sh
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MY_NUM=100
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SHELL=/bin/bash
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TERM=xterm
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USER=demouser
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LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca:...
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MAIL=/var/mail/demouser
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PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
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PWD=/home/demouser
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LANG=en_US.UTF-8
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MY_PI=3.142
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SHLVL=1
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HOME=/home/demouser
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LOGNAME=demouser
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MY_MESSAGE=Hello World
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LESSOPEN=| /usr/bin/lesspipe %s
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LESSCLOSE=/usr/bin/lesspipe %s %s
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_=/usr/bin/printenv
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$
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```
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### Hints
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Setting values to environment variables
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In order to set a value to an existing environment variable, we use an assignment expression. For instance, to set the value of the "LANG" variable to "he_IL.UTF-8", we use the following command:
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```console
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$ LANG=he_IL.UTF-8
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```
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If we use an assignment expression for a variable that doesn't exist, the shell will create a shell variable, which is similar to an environment variable but does not influence the behaviour of other applications.
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A shell variable can be exported to become an environment variable with the export command. To create the "EDITOR" environment variable and assign the value "nano" to it, you can do:
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```console
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$ EDITOR=nano
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$export EDITOR
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```
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> You have to use Man or Google to know more about commands flags, in order to solve this exercise!
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> Google and Man will be your friends!
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