Shell Scripting
Last updated
Last updated
Notes on shell scripting, as well as some zsh- and bash-specific stuff.
zsh has two representations for array variables like PATH and CDPATH, of which the lower case variant is an actual array
~ is a special character. Therefore, if you use it in a string variable and then try to do something with it, ~ will be evaluated literally, and not expanded to the value of $HOME. So use $HOME in these cases instead
Functions can be declared with/without function keyword and parens
my_function (), function my_function, etc
To pass arguments to a function, just use spaces
my_function "hello" "world"
If passing variables, sometimes it's good practice to put them in quotes in case the variables have spaces in them
The export keyword is only necessary when sub-processes need access to the variable
So if you don't use export, when you execute programs they won't have access to the variable. But the resulting shell will
To do string transformation on strings in zsh upon expansion, use
To rename the current directory: mv ../current_dir ../new_dir_name or mv ../{test,test2} (uses brace expansion for brevity)
(tl;dr: there's not a great way to do this). This would be nice for code readability
Can't assign variable to command exit status directly
But can get around it using $?:
(grep foo bar.txt); var1=$?
Can get around this if you need to by using this guy instead: ꞉ -- it's a different character but looks pretty similar
For conditionals, 0 is truthy and 1 is falsey
For multline string usage, use
For stripping trailing characters, use