bash - 这个 shell 脚本中的 ${1%..} 是什么意思？

Question

我有这样的脚本，

latex $1
asy ${1%.tex}.asy

我知道如果 $1=test.tex，那么 ${1%.tex}.asy 将是 test-1.asy ，但是这里的 1%. 是什么意思？如果我想让 ${1%.tex}.asy 成为 test.asy，我该怎么办？

Answer 1

来自 Bash Reference Manual :

${parameter%word}

${parameter%%word}

The word is expanded to produce a pattern just as in filename expansion. If the pattern matches a trailing portion of the expanded value of parameter, then the result of the expansion is the 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 positional 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.

所以如果 $1 扩展为 text.tex 那么 ${1%.tex} 扩展为 text .