このスクリプトを理解していません。
getopt_simple()
{
echo "getopt_simple()"
echo "Parameters are '$*'"
until [ -z "$1" ]
do
echo "Processing parameter of: '$1'"
if [ ${1:0:1} = '/' ]
then
tmp=${1:1} # Strip off leading '/' . . .
parameter=${tmp%%=*} # Extract name.
value=${tmp##*=} # Extract value.
echo "Parameter: '$parameter', value: '$value'"
eval $parameter=$value
fi
shift
done
}
if [ ${1:0:1} = '/' ]
上記で書いたコードの後に助けが必要です。私の質問は次のとおりです。
- if文では何が起こりますか?
- ここで ":"は何を意味しますか?
ベストアンサー1
1行に1つの新しい構文要素しかありません。これは良いことです。
関連部分を含む各行にコメントを付けます。man bash
役に立つかもしれませんし、他の答えと組み合わせることもできます。
パラメータから$1
0から始まる1つの文字を削除し、それが1つであることを確認してください/
。
if [ ${1:0:1} = '/' ]
${parameter:offset}
${parameter:offset:length}
Substring Expansion. Expands to up to length characters of the
value of parameter starting at the character specified by off‐
set. If parameter is @, an indexed array subscripted by @ or *,
or an associative array name, the results differ as described
below. If length is omitted, expands to the substring of the
value of parameter starting at the character specified by offset
and extending to the end of the value. length and offset are
arithmetic expressions (see ARITHMETIC EVALUATION below).
If offset evaluates to a number less than zero, the value is
used as an offset in characters from the end of the value of
parameter. If length evaluates to a number less than zero, it
is interpreted as an offset in characters from the end of the
value of parameter rather than a number of characters, and the
expansion is the characters between offset and that result.
Note that a negative offset must be separated from the colon by
at least one space to avoid being confused with the :- expan‐
sion.
char 0を保持し、1から最後まで文字を取得します$1
。
tmp=${1:1} # Strip off leading '/' . . .
上記の最初のケースを参照してください。
このようなパラメータの場合、--foo=bar
'=*'に一致するテキストはできるだけ右から左に切り捨てられます(処理を考慮--foo=bar=baz
)。
parameter=${tmp%%=*} # Extract name.
${parameter%word}
${parameter%%word}
Remove matching suffix pattern. The word is expanded to produce
a pattern just as in pathname expansion. If the pattern matches
a trailing portion of the expanded value of parameter, then the
result of the expansion is the expanded value of parameter with
the shortest matching pattern (the ``%'' case) or the longest
matching pattern (the ``%%'' case) deleted. If parameter is @
or *, the pattern removal operation is applied to each posi‐
tional parameter in turn, and the expansion is the resultant
list. If parameter is an array variable subscripted with @ or
*, the pattern removal operation is applied to each member of
the array in turn, and the expansion is the resultant list.
このようなパラメータの場合、--foo=bar
「* =」に一致するテキストはできるだけ左から右に切り捨てられます(処理を考慮--foo=bar=baz
)。
value=${tmp##*=} # Extract value.
${parameter#word}
${parameter##word}
Remove matching prefix pattern. The word is expanded to produce
a pattern just as in pathname expansion. If the pattern matches
the beginning of the value of parameter, then the result of the
expansion is the expanded value of parameter with the shortest
matching pattern (the ``#'' case) or the longest matching pat‐
tern (the ``##'' case) deleted. If parameter is @ or *, the
pattern removal operation is applied to each positional parame‐
ter in turn, and the expansion is the resultant list. If param‐
eter is an array variable subscripted with @ or *, the pattern
removal operation is applied to each member of the array in
turn, and the expansion is the resultant list.
(注:例ではasとは--foo=bar=baz
サポートしていませんが、asとはサポートしています。)
--foo
bar=baz
--foo
baz
出典:一部パラメータ拡張存在するman bash
、
man bash | less '+/Parameter Expansion'
(またはより短くman bash | less '+/##'
)