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linux shell實現(xiàn)獲取用戶輸入指定范圍的單個字符的兩種方法

更新時間：2013年03月02日 19:51:37 作者：

用shell實現(xiàn)的，要求獲取用戶輸一個字符a-zA-Z實現(xiàn)方法如下，需要的朋友可以參考下

方法一：

echo `echo {a..z}``echo {A..Z}` > /tmp/letterfile
while read -p "please input a letter: " letter
do
    ((`awk -v var="$letter" 'BEGIN{print length(var)}'` == 1)) && grep -q $letter /tmp/tmpfile && break
done
rm -f /tmp/letterfile
echo "you input letter $letter "

[root@station1 ~]# cat a.sh

復(fù)制代碼代碼如下:

echo `echo {a..z}``echo {A..Z}` > /tmp/letterfile
while read -p "please input a letter: " letter
do
((`awk -v var="$letter" 'BEGIN{print length(var)}'` == 1)) && grep -q $letter /tmp/tmpfile && break
done
rm -f /tmp/letterfile
echo "you input letter $letter "

[root@station1 ~]# chmod +x a.sh
[root@station1 ~]# ./a.sh
please input a letter: 123
please input a letter: abc
please input a letter: 4
please input a letter: &
please input a letter: (
please input a letter: a
you input letter a
[root@station1 ~]#

最初使用expr length $letter 替代 wk -v var="$letter" 'BEGIN{print length(var)}'的，但是，當(dāng)輸入*等特殊字符時，會報錯。
如下：
[root@station1 ~]# cat data

復(fù)制代碼代碼如下:

while read -p "please input a letter: " letter
do
((`expr length $letter` == 1)) && expr $letter : [[:alnum:]] > /dev/null && break
done
echo "you input letter $letter "

[root@station1 ~]# bash data
please input a letter: 123
please input a letter: abc
please input a letter: a
you input letter a
[root@station1 ~]# bash data
please input a letter: *
expr: 語法錯誤
data: line 3: ((: == 1: syntax error: operand expected (error token is "== 1")
please input a letter:

來看方法二：

復(fù)制代碼代碼如下:

while read -p "please input a letter: " letter
do
[[ `echo $letter | awk '/^[[:alpha:]]$/{print "1"}'` -eq 1 ]] && break
done
echo "you input letter $letter "

如下：
[root@station1 ~]# cat b.sh

復(fù)制代碼代碼如下:

while read -p "please input a letter: " letter
do
[[ `echo $letter | awk '/^[[:alpha:]]$/{print "1"}'` -eq 1 ]] && break
done
echo "you input letter $letter "

[root@station1 ~]# chmod +x b.sh
[root@station1 ~]# ./b.sh
please input a letter: *
please input a letter: abc
please input a letter: 234
please input a letter: )
please input a letter: T
you input letter T
[root@station1 ~]#

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