1、判断一个字符串是否只有字母组成，可以借助于grep命令，结合正则表达式来进行判断，字符有[A-Z]这26个字符组成，只要发现不属于这26个字符的字符，即表示不是纯字母的字符串。编写如下代码:while ((1));do read -p "input string:" var; if [[ $var == q || $var == Q ]];then exit; fi echo "$var" | grep [^a-z] >/dev/null && echo "$var: not character" || echo "$var: character"done
2、如上图所示的运行结果，GOOD做为输入，就判断错了，原因是没有考虑大写字母的问题。所以修改代码如下：while ((1));do read -p "input string:" var; if [[ $var == q || $var == Q ]];then exit; fi echo "$var" | grep [^a-z\|A-Z] >/dev/null && echo "$var: not character" || echo "$var: character"done
