書き方
リファレンス
参考：
Bash Reference Manual (all in one page) | gnu.org
Bash Reference Manual (separate contents) | gnu.org
変数
参考：
Operations on variables – Bash Guide for Beginners | The Linux Documentation Project
$@ と $* の違い
#! /usr/bin/env bash time "$@"
参考：
What does “$@” mean in Bash? – Quora
Bash $@ (Dollar At Variable) Loses Quote Characters | Biostar
変数名を取り出す
$ i_want_to_know_variable_name="hey!"
$ echo "${!i_want_to_know_variable_name@}"
参考：
In bash, how can I echo the variable name, not the variable value? – Unix & Linux Stack Exchange
indirect variable expansion
$ fire="red!"
$ color="fire"
$ echo "${!color}"
red!
参考：
Bash expand variable in a variable – Stack Overflow
How to use call-by-reference on an argument in a bash function – Unix & Linux Stack Exchange
nameref
参照渡しにする。渡された外部の変数を書き換えることができる。
$ function say () \
{ \
local -n ref=$1; \
ref="bye"; \
}
$ greeting="hello"
$ echo $greeting
hello
$ say greeting
$ echo $greeting
bye
参考：
Shell Parameters – Bash Reference Manual | gnu.org
The declare builtin command | Bash Hackers Wiki
Passing arguments by reference – Stack Overflow
Shell variables in a for loop – Unix & Linux Stack Exchange
間接参照
参考：
Indirect References – Advanced Bash-Scripting Guide | The Linux Documentation Project
クォーティング
- Weak quoting:
"$var is replaced" - Strong quoting:
'kind of $var is left as is' - ANSI-C quoting:
$'kind of \e is replaced escape sequence' - Locale Translation:
$"string can be localized"
参考：
Quotes and escaping | Bash Hackers Wiki
Quoting characters | Bash Guide for Beginners
ANSI-C Quoting – Bash Reference Manual | gnu.org
Locale Translation – Bash Reference Manual | gnu.org
ダブルクォーテーション
参考：
How to escape a double quote inside double quotes? – Stack Overflow
Why do we double-quote a dollar sign evaluation in Bash? – Unix & Linux Stack Exchange
ダブルクォーテーションとシングルクォーテーションの違い
参考：
ShellScript のダブルクォートとシングルクォートの違い – Qiita
ANSI-C クォーティング
参考：
ANSI-C Quoting – Bash Reference Manual | gnu.org
How does the leading dollar sign affect single quotes in Bash? – Stack Overflow
How to escape quotes in shell? – Unix & Linux Stack Exchange
ロケールトランスレーション
参考：
Locale Translation – Bash Reference Manual | gnu.org
What does it mean to have a $”dollarsign-prefixed string” in a script? – Unix & Linux Stack Exchange