====================================
While statements
====================================

while something happens; do
  echo a
  echo b
done

---

(program
  (while_statement
    (command (command_name (word)) (word))
    (do_group
      (command (command_name (word)) (word))
      (command (command_name (word)) (word)))))

====================================
While statements with IO redirects
====================================

while read line; do
  echo $line
done < <(cat file)

---

(program
  (while_statement
    (command (command_name (word)) (word))
    (do_group
      (command (command_name (word)) (simple_expansion (variable_name))))
    (file_redirect (process_substitution
      (command (command_name (word)) (word))))))

====================================
For statements
====================================

for a in 1 2 $(seq 5 10); do
  echo $a
done

for ARG; do
  echo $ARG
  ARG=''
done

---

(program
  (for_statement
    (variable_name)
    (word)
    (word)
    (command_substitution (command (command_name (word)) (word) (word)))
    (do_group
      (command (command_name (word)) (simple_expansion (variable_name)))))
  (for_statement
    (variable_name)
    (do_group
      (command (command_name (word)) (simple_expansion (variable_name)))
      (variable_assignment (variable_name) (raw_string)))))

====================================
If statements
====================================

if cat some_file | grep -v ok; then
  echo one
elif cat other_file | grep -v ok; then
  echo two
else
  exit
fi

---

(program
  (if_statement
    (pipeline
      (command (command_name (word)) (word))
      (command (command_name (word)) (word) (word)))
    (command (command_name (word)) (word))
    (elif_clause
      (pipeline
        (command (command_name (word)) (word))
        (command (command_name (word)) (word) (word)))
      (command (command_name (word)) (word)))
    (else_clause
      (command (command_name (word))))))

====================================
If statements with conditional expressions
====================================

if [ "$(uname)" == 'Darwin' ]; then
  echo one
fi

---

(program
  (if_statement
    (bracket_command
      (string (command_substitution (command (command_name (word)))))
      (raw_string))
    (command (command_name (word)) (word))))

====================================
Case statements
====================================

case "opt" in
  a)
    echo a
    ;;

  b)
    echo b;;
esac

case "$Z" in
  ab*|cd*) ef
esac

---

(program
  (case_statement (string)
    (case_item (word)
      (command (command_name (word)) (word)))
    (case_item (word)
      (command (command_name (word)) (word))))
  (case_statement (string (simple_expansion (variable_name)))
    (case_item (word) (word)
      (command (command_name (word))))))

===============================
Subshells
===============================

(
  ./start-server --port=80
) &

---

(program
  (subshell (command (command_name (word)) (word))))

===============================
Function definitions
===============================

do_something() {
  echo ok
}

function do_something_else() {
  echo ok
}

function do_yet_another_thing {
  echo ok
} 2>&1

---

(program
  (function_definition
    (word)
    (compound_statement (command (command_name (word)) (word))))
  (function_definition
    (word)
    (compound_statement (command (command_name (word)) (word))))
  (function_definition
    (word)
    (compound_statement (command (command_name (word)) (word)))
    (file_redirect (file_descriptor) (word))))

=========================================
Variable declaration: declare & typeset
=========================================

declare var1
typeset -i -r var2=42 var3=10

---

(program
  (declaration_command (variable_name))
  (declaration_command (word) (word)
    (variable_assignment (variable_name) (word))
    (variable_assignment (variable_name) (word))))

=========================================
Variable declaration: readonly
=========================================

readonly var1
readonly var2=42

---

(program
  (declaration_command (variable_name))
  (declaration_command (variable_assignment (variable_name) (word))))

=========================================
Variable declaration: local
=========================================

local a=42 b
local -r c

---

(program
  (declaration_command
    (variable_assignment (variable_name) (word))
    (variable_name))
  (declaration_command
    (word)
    (variable_name)))

=========================================
Variable declaration: export
=========================================

export PATH
export FOOBAR PATH="$PATH:/usr/foobar/bin"

---

(program
  (declaration_command (variable_name))
  (declaration_command
    (variable_name)
    (variable_assignment (variable_name) (string (simple_expansion (variable_name))))))

===========================================
Expressions passed to declaration commands
===========================================

export "$(echo ${key} | tr [:lower:] [:upper:])=${p_key#*=}"

---

(program
  (declaration_command
    (string
      (command_substitution
        (pipeline
          (command (command_name (word)) (expansion (variable_name)))
          (command (command_name (word)) (concatenation (word)) (concatenation (word)))))
      (expansion (variable_name) (word)))))

=========================================
Unset commands
=========================================

unset A
unset "$variable_name"
unsetenv -f ONE TWO

---

(program
  (unset_command (variable_name))
  (unset_command (string (simple_expansion (variable_name))))
  (unset_command (word) (variable_name) (variable_name)))