101 lines
1.7 KiB
Plaintext
101 lines
1.7 KiB
Plaintext
=============================
|
|
Literal words
|
|
=============================
|
|
|
|
echo a
|
|
echo a b
|
|
|
|
---
|
|
|
|
(program
|
|
(command (command_name) (word))
|
|
(command (command_name) (word) (word)))
|
|
|
|
=============================
|
|
Simple variable expansions
|
|
=============================
|
|
|
|
echo $abc
|
|
|
|
---
|
|
|
|
(program
|
|
(command (command_name) (simple_expansion (variable_name))))
|
|
|
|
=============================
|
|
Variable expansions
|
|
=============================
|
|
|
|
echo ${abc}
|
|
echo ${abc:-def}
|
|
|
|
---
|
|
|
|
(program
|
|
(command (command_name) (expansion (variable_name)))
|
|
(command (command_name) (expansion (variable_name) (word))))
|
|
|
|
===================================
|
|
Other variable expansion operators
|
|
===================================
|
|
|
|
cat ${BAR} ${ABC=def} ${GHI:?jkl}
|
|
|
|
---
|
|
|
|
(program
|
|
(command
|
|
(command_name)
|
|
(expansion (variable_name))
|
|
(expansion (variable_name) (word))
|
|
(expansion (variable_name) (word))))
|
|
|
|
=============================
|
|
Command substitutions
|
|
=============================
|
|
|
|
echo `echo hi`
|
|
echo $(echo $(echo hi))
|
|
|
|
---
|
|
|
|
(program
|
|
(command
|
|
(command_name)
|
|
(command_substitution (command (command_name) (word))))
|
|
(command
|
|
(command_name)
|
|
(command_substitution (command
|
|
(command_name)
|
|
(command_substitution (command
|
|
(command_name)
|
|
(word)))))))
|
|
|
|
=============================
|
|
Single quoted strings
|
|
=============================
|
|
|
|
echo 'a b' 'c d'
|
|
|
|
---
|
|
|
|
(program
|
|
(command (command_name) (raw_string) (raw_string)))
|
|
|
|
=============================
|
|
Double quoted strings
|
|
=============================
|
|
|
|
echo "a" "b"
|
|
echo "a ${b} c" "d $e"
|
|
|
|
---
|
|
|
|
(program
|
|
(command (command_name)
|
|
(string)
|
|
(string))
|
|
(command (command_name)
|
|
(string (expansion (variable_name)))
|
|
(string (simple_expansion (variable_name)))))
|