Minishell Documentation

Tests to be performed while evaluating the Minishell / while building up Minishell:

ENV VARIABLES:

• when launching bash (from any application), the env command will print the environmental variables
• if a student unsets the variables before launching Minishell, the Minishell program must be able to replicate bash behaviour, according to the subject;
  1. unset PATH
  2. launch minishell
  3. echo $PATH should result in the PATH variable being printed
  4. env should result in the environmental list to be printed, including the PATH variable
  5. same for PWD -> if someone unsets PWD, this variable must be recreated when launching Minishell and included in the env list

For PWD only, please note that if you are positioned in a symlink when opening minishell, the echo $PWD command must deliver the correct path you are on.

STEPS to replicate this behavior:

• in the minishell directory: mkdir testdir
• ln -s testdir link
• move into the link: cd link
• create another directory: mkdir testdir2
• create another link: ln -s testdir2 link2
• now, if you write pwd, you should be positioned into your first link. The result should be something like: ~>/..../.../minishell/link
• now launch minishell from this position, e.g.: ../minishell
• now write pwd -> the result should be the same as the one you had previously, before launching minishell: ~>/..../.../minishell/link
• check PWD -> echo $PWD, should be the same as the command pwd
• move into the second link: cd link2
• pwd should result in: ~>/..../.../minishell/link/link2
• echo $PWD should also result in ~>/..../.../minishell/link/link2
• unset PWD
• echo $PWD should result in an empty newline
• pwd should still print the path: ~>/..../.../minishell/link/link2
• cd ..
• env should present a list without PWD in it
• echo $PWD should print ~>/..../.../minishell/link
• pwd should also print ~>/..../.../minishell/link
• echo $OLDPWD should result in an empty space

ALTERNATIVELY, a student can choose NOT to replicate this behaviour, but to simply protect against this behaviour. This means that a student must make sure the code doesn't segfault / crash and that it throws an error / finds an alternative to not having a PATH

BUILTINS

echo

• echo lala => lala\n
• echo $PWD => should print the value of the PWD env variable followed by a newline
• echo -n lol => lol
• echo -n -nnnnn -nnnnnnnn => (no empty lines; nothing to be printed)
• echo -nnnnnn -nnnnnn -nnnnnk => -nnnnnk
• echo-nnnnnn => errror
• pwd prints the current folder one is in, no matter if $PATH exists or not
• must correctly print symlinks, if within a symlink structure, such as: :~>/..../.../minishell/symlink1/symlink2/testdir3/symlink4

export

• export ABC=lala must add to the env list the variable ABC with the value lala
• export A*$#$#BC=lala must throw an error
• export must print a list with all the env variables, displayed in alphabetical order, such as: declare -x USER="username"
• export ABC=lala ADF=testing AJH=oops should add all 3 variables to the env
• export ABC=lala and export ABC=lala will export the ABC variable only once, with the value 'lala'
• export ABC=lala and export ABC=lolo will export the ABC variable only once, but the second command will change its value to 'lolo'

unset

• unset ABC will unset the variable ABC, removing it from the env variables
• unset ABC ABD ABF will unset all 3 variables from env, if they are present in the env variables

cd

• cd / should change directory to /
• cd /home/user/Documents should change the directory to /home/user/Documents
• cd /home/user/Documents/symlink and then write pwd -> the display should be /home/user/Documents/symlink and not /home/user/Documents/*directory towards which the link points to*
• cd $OLDPWD should change directory to the one indicated by $OLDPWD
• cd .. should change the directory to the one above