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需求：要求获取用户输一个字符a-zA-Z：
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 $letter "
[root@station1 ~]# cat a.sh
复制代码代码如下:
echo `echo {a..z}``echo {A..Z}` > /tmp/letterfile
while read -p "please input a letter: " letter do ((`awk -v var="$letter" 'BEGIN{print length(var)}'` == 1)) && grep -q $letter /tmp/tmpfile && break done rm -f /tmp/letterfile echo "you input letter $letter "
[root@station1 ~]# chmod +x a.sh
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。
复制代码代码如下:
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
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：
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 "
[root@station1 ~]# chmod +x b.sh |