shell大小写字母转换

#!/bin/sh
#----------------------------------------------------------
# [:upper:][A-Z]
# [:lower:][a-z]
# [:digit:] [ 0 - 9 ]
# [:alnum:] [ 0 - 9 a - z A-Z]
# [:space:] 空格或tab键
# [:alpha:][a-zA-Z]
#----------------------------------------------------------
# tr
for f in *
do
  mv $f `echo $f | tr "[:upper:]" "[:lower:]" `
done

#awk 

#把当前目录下的所有小写文件名都改为大写文件名。 

ls | awk '{printf("mv %s %s\n", $0, toupper($0))|"sh"}'

#把当前目录下的所有大写文件名都改为小写文件名。 

ls | awk '{printf("mv %s %s\n", $0, tolower($0))|"sh"}'

#sed 

cat file | sed 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/'