bash

Manual

Special Parameters, Positional Parameters

*	($*) is equivalent to "$1c$2c…", where c is the first character of the value of the IFS variable
@	($@) is equivalent to "$1" "$2"
#	($#) is the number of positional parameters in decimal
?	($?) Expands to the exit status of the most recently executed foreground pipeline.
-	($-) Expands to the current option flags
$	($$) is the process ID of the shell
	($!) is the process ID of the job most recently placed into the background
0	($0) is the name of the shell or shell script
_	($_) is the same as $0 in script, or the arguments of the last command.
int	$1,$2,... are the Positional Parameters

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Bourne Shell Variables

man
Parameter and Variable Index

CDPATH
HOME
IFS	separator characters
MAIL
MAILPATH
OPTARG
OPTIND
PATH
PS1	primary prompt string	'\s-\v\$ '
PS2	secondary prompt string	‘> ’

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Bash Variables

man
Parameter and Variable Index

BASH	The full pathname Bash
BASHOPTS	list of shell options	colon-separated
BASHPID	pid	assoc.arr
BASH_ALIASES	aliases
BASH_ARGC	argc	arr
BASH_ARGV	argv	arr
BASH_CMDS	command	assoc.arr
BASH_COMMAND	current command
BASH_COMPAT	compatibility level
BASH_ENV	env
BASH_EXECUTION_STRING	arg to -c
BASH_LINENO	line no.	arr
BASH_REMATCH	rematch	arr,ro
BASH_SOURCE	src fname	arr
BASH_SUBSHELL	subshell	int
BASH_VERSINFO	version	arr,ro
BASH_VERSINFO[0]	major versoin number	release
BASH_VERSINFO[1]	minor version number	version
BASH_VERSINFO[2]	pathc level
BASH_VERSINFO[3]	build
BASH_VERSINFO[4]	release status	(e.g., beta1)
BASH_VERSINFO[5]	value of MACHTYPE
BASH_VERSION	version number of current Bash
BASH_XTRACEFD	-x trace file desc.
CHILD_MAX
COLUMNS
COMP_CWORD
COMP_LINE
COMP_POINT
COMP_TYPE
COMP_KEY
COMP_WORDBREAKS
COMP_WORDS
COMPREPLY
COPROC
DIRSTACK
EMACS
ENV
EUID
FCEDIT
FIGNORE
FUNCNAME
FUNCNEST
GLOBIGNORE
GROUPS
histchars
HISTCMD
HISTCONTROL
HISTFILE
HISTFILESIZE
HISTIGNORE
HISTSIZE
HISTTIMEFORMAT
HOSTFILE
HOSTNAME
HOSTTYPE
IGNOREEOF
INPUTRC
LANG	locale
LC_ALL	override LANG,LC_
LC_COLLATE
LC_CTYPE
LC_MESSAGES
LC_NUMERIC
LINENO
LINES
MACHTYPE
MAILCHECK
MAPFILE
OLDPWD
OPTERR
OSTYPE
PIPESTATUS
POSIXLY_CORRECT
PPID
PROMPT_COMMAND
PROMPT_DIRTRIM
PS3
PS4
PWD
RANDOM
READLINE_LINE
READLINE_POINT
REPLY
SECONDS
SHELL
SHELLOPTS
SHLVL
TIMEFORMAT
TMOUT
TMPDIR
UID

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One Liner

One Liner
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.bashrc

.bashrc
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tips

Bash command line and input limit

for fork()/exec()

ARG_MAX:Maximum length of argument to the exec functions

$ getconf ARG_MAX
2097152

text colors

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Prompt

PS1
#!/bin/bash
# bash text color samples

#ESCAPE \e color
echo $'\e[0m \\e[0;30m \e[0;30m black'
echo $'\e[0m \\e[0;31m \e[0;31m red'
echo $'\e[0m \\e[0;32m \e[0;32m green'
echo $'\e[0m \\e[0;33m \e[0;33m yellow'
echo $'\e[0m \\e[0;34m \e[0;34m blue'
echo $'\e[0m \\e[0;35m \e[0;35m magenta'
echo $'\e[0m \\e[0;36m \e[0;36m cyan'
echo $'\e[0m \\e[0;37m \e[0;37m light gray'
echo $'\e[0m \\e[1;30m \e[1;30m dark gray'
echo $'\e[0m \\e[1;31m \e[1;31m red'
echo $'\e[0m \\e[1;32m \e[1;32m green'
echo $'\e[0m \\e[1;33m \e[1;33m yellow'
echo $'\e[0m \\e[1;34m \e[1;34m blue'
echo $'\e[0m \\e[1;35m \e[1;35m magenta'
echo $'\e[0m \\e[1;36m \e[1;36m cyan'
echo $'\e[0m \\e[1;37m \e[1;37m white'
echo $'\e[0m \\e[0;40m \e[0;40m black'
echo $'\e[0m \\e[0;41m \e[0;41m red'
echo $'\e[0m \\e[0;42m \e[0;42m green'
echo $'\e[0m \\e[0;43m \e[0;43m yellow'
echo $'\e[0m \\e[0;44m \e[0;44m blue'
echo $'\e[0m \\e[0;45m \e[0;45m magenta'
echo $'\e[0m \\e[0;46m \e[0;46m cyan'
echo $'\e[0m \\e[0;47m \e[0;47m light gray'
echo $'\e[0m \\e[1;40m \e[1;40m dark gray'
echo $'\e[0m \\e[1;41m \e[1;41m red'
echo $'\e[0m \\e[1;42m \e[1;42m green'
echo $'\e[0m \\e[1;43m \e[1;43m yellow'
echo $'\e[0m \\e[1;44m \e[1;44m blue'
echo $'\e[0m \\e[1;45m \e[1;45m magenta'
echo $'\e[0m \\e[1;46m \e[1;46m cyan'
echo $'\e[0m \\e[1;47m \e[1;47m white'
echo $'\e[0m \\e[1:31m \\e[1;47m \e[0;31m \e[1;47m red on white'
echo $'\e[0m \\ep0m \e[0m reset'
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