コマンドのパラメータをスクリプトに転送するために2つの変数（$ @、$ *）を使用する目的は何ですか？ [コピー]

簡単で独創的な説明は次のとおりです。

• $*設定されたすべてのパラメータは文字列です（パラメータは最初の文字で区切られています$IFS）。
• $@各パラメータは異なる文字列です（改行文字で区切られたパラメータ）。

からman bash：

* Expands to the positional parameters, starting from one.  When the expansion is not within  dou‐
  ble  quotes, each positional parameter expands to a separate word.  In contexts where it is per‐
  formed, those words are subject to further word splitting  and  pathname  expansion.   When  the
  expansion occurs within double quotes, it expands to a single word with the value of each param‐
  eter separated by the first character of the IFS special variable.  That is, "$*" is  equivalent
  to  "$1c$2c...",  where  c  is  the first character of the value of the IFS variable.  If IFS is
  unset, the parameters are separated by spaces.  If IFS is null, the parameters are joined  with‐
  out intervening separators.
@ Expands  to the positional parameters, starting from one.  When the expansion occurs within dou‐
  ble quotes, each parameter expands to a separate word.  That is, "$@" is equivalent to "$1" "$2"
  ...   If  the double-quoted expansion occurs within a word, the expansion of the first parameter
  is joined with the beginning part of the original word, and the expansion of the last  parameter
  is  joined  with  the  last part of the original word.  When there are no positional parameters,
  "$@" and $@ expand to nothing (i.e., they are removed).

さらに:

• "$*"次に展開"arg1 arg2 arg3 …"
• "$@"次に展開"arg1" "arg2" "arg3" …

したがって、より"$@"安全です。$*古いことがあり、以前のバージョンとの互換性のために存在します。

からman bash：

Special Parameters
   The  shell treats several parameters specially.  These parameters may only
   be referenced; assignment to them is not allowed.
   *      Expands to the positional parameters, starting from one.  When  the
          expansion  is  not  within double quotes, each positional parameter
          expands to a separate word.  In contexts  where  it  is  performed,
          those  words  are  subject  to  further word splitting and pathname
          expansion.  When the expansion  occurs  within  double  quotes,  it
          expands to a single word with the value of each parameter separated
          by the first character of the IFS special variable.  That is,  "$*"
          is equivalent to "$1c$2c...", where c is the first character of the
          value of the IFS variable.  If IFS is  unset,  the  parameters  are
          separated  by  spaces.   If  IFS is null, the parameters are joined
          without intervening separators.
   @      Expands to the positional parameters, starting from one.  When  the
          expansion  occurs within double quotes, each parameter expands to a
          separate word.  That is, "$@" is equivalent to "$1"  "$2"  ...   If
          the  double-quoted expansion occurs within a word, the expansion of
          the first parameter is joined with the beginning part of the origi‐
          nal  word,  and  the expansion of the last parameter is joined with
          the last part of the original word.  When there are  no  positional
          parameters, "$@" and $@ expand to nothing (i.e., they are removed).

4つの場合、特にスペースを含むパラメータを比較してください。

for i in $*; do echo "$i"; done
for i in $@; do echo "$i"; done
for i in "$*"; do echo "$i"; done
for i in "$@"; do echo "$i"; done

特殊パラメータ $* と $@:

すべてのコマンドラインパラメータに一度にアクセスできる特別なパラメータがあります。 $ *と$ @は二重引用符 ""で囲まない限り同じ効果を持ちます。

両方のパラメータはすべてのコマンドラインパラメータを指定しますが、特殊文字「$ *」はリスト全体を空白の1つのパラメータとして使用し、「$ @」特殊パラメータはリスト全体を別々のパラメータとして使用します。に分割します。

$ *または$ @特殊パラメータを使用してシェルスクリプトを作成して、不明な数のコマンドライン引数を処理できます。