shell总结

1、Compound commands

Compound commands overview
Grouping
{ …; }	command grouping
( … )	command grouping in a subshell
Conditionals
[[ ... ]]	conditional expression
if …; then …; fi	conditional branching
case … esac	pattern-based branching
Loops
for word in …; do …; done	classic for-loop
for ((x=1; x<=10; x++)); do ...; done	C-style for-loop
while …; do …; done	while loop
until …; do …; done	until loop
Misc
(( ... ))	arithmetic evaluation
select word in …; do …; done	user selections

2、Expansions and substitutions

Introduction to expansions and substitutions
{A,B,C} {A..C}	Brace expansion
~/ ~root/	Tilde expansion
$FOO ${BAR%.mp3}	Parameter expansion
`command` $(command)	Command substitution
<(command) >(command)	Process substitution
$((1 + 2 + 3)) $[4 + 5 + 6]	Arithmetic expansion
Hello <---> Word!	Word splitting
/data/*-av/*.mp?	Pathname expansion

3、Builtin Commands

Declaration commands Commands that set and query attributes/types, and manipulate simple datastructures.		Alt	Type
declare	Display or set shell variables or functions along with attributes.	typeset	builtin
export	Display or set shell variables, also giving them the export attribute.	-	special builtin
eval	A common misspelling of "evil"	-	special builtin
local	Declare variables as having function local scope.	-	builtin
readonly	Mark variables or functions as read-only.	declare -r	special builtin
unset	Unset variables and functions.	-	special builtin
shift	Shift positional parameters	-	special builtin

Control flow and data processing Commands that operate on data and/or affect control flow.		Alt	Type
colon	"true" null command	true	special builtin
dot	Source external files	source	special builtin
false	Fail at doing nothing	-	builtin
continue / break	continue with or break out of loops.	-	special builtin
let	Arithmetic evaluation - an old fashioned way.	-	builtin
return	Break out of a function, returning the specified exit status.	-	special builtin
[	The classic test command.	test	builtin
Process and Job control Commands related to jobs, signals, process groups, subshells.		Alt	Type
exec	Replace the shell, set redirections.	-	special builtin
exit	Exit the shell.	-	special builtin
trap	Set traps.	-	special builtin
times	Display process times.	-	special builtin
wait	Wait for background jobs and asynchronous lists.	-	builtin

I/O Commands for reading/parsing input, or producing/formatting output of standard streams.		Alt	Type
coproc	Co-processes: Run a compound command in the background with async I/O.	-	keyword
echo	Create output from args.	-	builtin
mapfile	Create arrays from lines of input	readarray	builtin
printf	"advanced echo."	-	builtin
read	Build variables or arrays from input streams.	-	builtin
Configuration and Debugging Commands that modify shell behavior, change special options, assist in debugging.		Alt	Type
caller	Identify/print execution frames.	-	builtin
set	Control positional parameters and shell behaviour.	-	special builtin
shopt	set/get shell options.	-	builtin

整理自：http://wiki.bash-hackers.org/start