Shell 参数扩展

hardie

#!/bin/sh

# {x..y[incr]},
# ~
echo a{a,c,b}e

echo ~

echo ~/foo

echo ~root/foo

echo ~+/foo

echo ~-/foo

# ${parameter:-word}

unset x;
y="abc def";
echo "/${x:-'XYZ'}/${y:-'XYZ'}/$x/$y/"

# ${parameter:=word}
unset x;
y="abc def";
echo "/${x:='XYZ'}/${y:='XYZ'}/$x/$y/"

# ${parameterword}
( unset x;
  y="abc def";
  echo "/${x'XYZ'}/${y'XYZ'}/$x/$y/" )>>so.txt 2>se.txt

# ${parameter:+word}
unset x;
y="abc def";
echo "/${x:+'XYZ'}/${y:+'XYZ'}/$x/$y/"

# ${parameterffset}
# ${parameterffset:length}
x="some value"
echo "${x:3}"
echo "${x:3:5}"

# ${!prefix*}
# ${!prefix@}

zhang=Zhang
firstname=zhang
firstx=xxxxx
firsty=yyyyy
echo ${firstname}
echo ${!firstname}
echo ${!first*}
echo ${!first@}
echo "\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\"
# ${!name[@]}
# ${!name

}
# bash 3.0 support ??

array=(a b c def)
echo ${array}
echo ${array

}
echo ${array[@]}
echo ${!array

}
echo ${!array[@]}

# ${#parameter}

firstname=zhang
echo ${#firstname}
echo ${#array[@]}
echo ${#array

}

# ${parameter#word}
# ${parameter##word}

x="a1 b1 c2 d2"
echo ${x#*1}
echo ${x##*1}

# ${parameter%word}
# ${parameter%%word}
echo ${x%1*}
echo ${x%%1*}

# ${parameter/pattern/string}
# ${parameter//pattern/string}
echo ${x/1/3}
echo ${x//1/3}

# ${parameter^pattern}
# ${parameter^^pattern}
# ${parameter,pattern}
# ${parameter,,pattern}

是如何用的？

yazi0127

LZ的脚本貌似是一个学习shell如果处理字符串的测试脚本？

hardie

${parameter^pattern}
${parameter^^pattern}
${parameter,pattern}
${parameter,,pattern}
This expansion modifies the case of alphabetic characters in parameter. The pattern is expanded to produce a pattern just as in pathname expansion. The ‘^’ operator converts lowercase letters matching pattern to uppercase; the ‘,’ operator converts matching uppercase letters to lowercase. The ‘^^’ and ‘,,’ expansions convert each matched character in the expanded value; the ‘^’ and ‘,’ expansions match and convert only the first character in the expanded value. If pattern is omitted, it is treated like a ‘?’, which matches every character. If parameter is ‘@’ or ‘*’, the case modification 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 case modification operation is applied to each member of the array in turn, and the expansion is the resultant list.

这个方式不知道是怎么用的