方法一:
复制代码代码如下:
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 $letter “
[root@station1 ~]# cat a.sh
代码如下:
echo `echo {a..z}“echo {A..Z}` > /tmp/letterfile
while read -p “please input a letter: ” letter
do
((`awk -v var=”$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,当输入*等特殊字符时,会报错。
如下:
[root@station1 ~]# cat data代码如下:
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: 语法错误
data: line 3: ((: == 1: syntax error: operand expected (error token is “== 1”)
please input a letter:来看方法二:
复制代码代码如下:
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代码如下:
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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