Improve installation script

mac-os-install.bash

@@ -1,18 +1,33 @@
 #!/usr/bin/env bash
 
 # If Homebrew is not installed
-if ! command -v brew &> /dev/null
+if
+  ! command -v brew &> /dev/null
 then
   # Install Homebrew
-  /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
+  bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
 fi
 
 # Install dependencies
 brew install bat fd fish fzf lsd mosh neovim ripgrep stow zoxide
 
 # Set fish as a default shell
-sudo echo '/usr/local/bin/fish' >> /etc/shells
-chsh -s /usr/local/bin/fish
+
+FISH=`which fish`
+SHELLS="/etc/shells"
+
+if
+  (test -f $SHELLS) &&
+  (test -z $(grep "$FISH" "$SHELLS"))
+then
+  sudo bash -c "echo \"$FISH\" >> \"$SHELLS\""
+fi
+
+if 
+  "$SHELL" != "$FISH"
+then
+  chsh -s "$FISH"
+fi
 
 # Symlink all configurations from .dotfiles
 stow .