Bash Shell 字符串切割

Some examples：

chj@linux-xzlr:Desktop\> AAA="hello First-of All"
chj@linux-xzlr:Desktop\> echo ${AAA#*-}
of All
chj@linux-xzlr:Desktop\> AAA=111-222
chj@linux-xzlr:Desktop\> echo ${AAA%-*}
111
chj@linux-xzlr:Desktop\> echo ${AAA#*-}
222
chj@linux-xzlr:Desktop\>

记住瞬间，精彩永恒
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1.
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chj@linux-xzlr:trunk\> AA="a bc d ef"
chj@linux-xzlr:trunk\> BB="d"
chj@linux-xzlr:trunk\> echo ${AA%%$BB*}
a bc
chj@linux-xzlr:trunk\> echo ${AA$BB}
bash: ${AA$BB}: bad substitution
chj@linux-xzlr:trunk\> echo ${AA#*$BB}
ef
chj@linux-xzlr:trunk\>

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2.
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cjash@linux-sdik:dl\> AAA=abcdef
cjash@linux-sdik:dl\> echo ${AAA:2}
cdef
cjash@linux-sdik:dl\> echo ${AAA-2}
abcdef
cjash@linux-sdik:dl\> echo ${AAA:-2}
abcdef
cjash@linux-sdik:dl\> echo ${AAA#2}
abcdef
cjash@linux-sdik:dl\> echo ${AAA#*2}
abcdef
cjash@linux-sdik:dl\> echo ${AAA 2}
bash: ${AAA 2}: bad substitution
cjash@linux-sdik:dl\> echo ${AAA$2}
bash: ${AAA$2}: bad substitution
cjash@linux-sdik:dl\> echo ${AAA: -2}
ef
cjash@linux-sdik:dl\> echo ${AAA%2}
abcdef
cjash@linux-sdik:dl\> echo ${AAA#*2}
abcdef
cjash@linux-sdik:dl\> echo ${AAA::2}
ab
cjash@linux-sdik:dl\>

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3.
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cjash@linux-sdik:ppp\> AAA=abcabcabc
cjash@linux-sdik:ppp\> echo ${AAA%${AAA: -2}}
abcabca
cjash@linux-sdik:ppp\>
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4.
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cjash@linux-sdik:ppp\> AAA=abcabcabc
cjash@linux-sdik:ppp\> echo ${AAA%${AAA: -2}}
abcabca
cjash@linux-sdik:ppp\>