Bash Cheat-Sheet Cheat Sheet (DRAFT) by arest

$0	Name of script
$1 - $10	Positional parameters #1 - #10
$#	Number of positional parameters
\"\$­*"	All parameters (single word)
"­$@"	All parameters (separate strings)
${#*} ${#@}	Number of parameters
$?	Return value
$$	Process ID (PID)
$-	Flags (using set )
$_	Last argument of previous command
$!	PID of last job run in background

${VAR}	Value of VAR
${VAR-­word}	If VAR not set, use ­word
${VAR:­-­word}	If VAR not set or null, use ­word
${VAR:=­word} ${VAR=word}	Assign default value. (position./spec.param. may not be assigned)
${VAR:?­ERR_MSG} ${VAR?­ERR_MSG}	Display Error Message if null or unset
${VAR:­+­word}	Use Alternate: null/unset - nothing, else - word
${VAR:­o­f­fs­et}	Substring
${VAR:o­ffs­et:­len­gth}	Substring with size length
${!VAR[@]} ${!VAR[*]}	List Array Keys
${#VAR}	Parameter length
${VAR#­m­atch}	Remove prefix
${VAR#­#­m­at­ch}	Remove prefix (longest)
${VAR%­m­atch}	Remove suffix
${VAR%­%­m­at­ch}	Remove suffix (longest)
${VAR/­p­a­tt­­ern­­/str}	Replace first match of pattern with str
${VAR/­p­a­tt­­ern­­/str}	Replace all match of pattern with str
${VAR^­p­a­tt­ern}	Uppercase match
${VAR^­^­p­at­­tern}	Uppercase all
${VAR,­p­a­tt­ern}	Lowercase match
${VAR,­,­p­at­­tern}	Lowercase all
${!VAR*} ${!VAR@}	Match all vars begginning with VAR

!!	Last command
!?foo	Last command containing foo
^foo^bar^	Last command containing foo , but substitute bar
!!:0	Last command word
!!:^	Last command's first argument
!$	Last command's last argument
!!:*	Last command's arguments
!!:x-y	Arguments x to y of last command
C-s	search forwards in history
C-r	search backwards in history

~-	Previous working directory
pushd tmp	Push tmp && cd tmp
popd	Pop && cd

ls a[b-dx]e	Globs abe, ace, ade, axe
ls a\{c,bl\}e	Globs ace, able
$(ls)	`ls` (but nestable!)

cmd > file	Redirect the standard output (stdout) of cmd to a file.
cmd 1> file
cmd 2> file
cmd >> file
cmd 2>> file
cmd &> file
cmd > file 2>&1
cmd > /dev/null
cmd 2> /dev/null
cmd &> /dev/null
cmd < file
cmd << EOL foo bar EOL
cmd <<- EOL <tab>foo <tab><tab>bar EOL
cmd <<< "­str­ing­"
exec 2> file
exec 3< file
exec 3> file
exec 3<> file
exec 3>&-
exec 4>&3
exec 4>&3-
echo "­foo­" >&3
cat <&3
(cmd1; cmd2) > file
{ cmd1; cmd2; } > file
exec 3<> /dev/t­cp/­hos­t/port
exec 3<> /dev/u­dp/­hos­t/port
cmd <(cmd1)
cmd < <(cmd1)
cmd <(cmd1) <(cmd2)
cmd1 >(cmd2)
cmd1 | cmd2
cmd1 |& cmd2
cmd | tee file
exec {filew­}> file
cmd 3>&1 1>&2 2>&3
cmd > >(cmd1) 2> >(cmd2)
cmd1 | cmd2 | cmd3 | cmd4 echo ${PIPE­STA­TUS[@]}