使用tr命令加密文件

加密，将file1加密成file2文件
tr "[a-m][n-z]" "[n-z][a-m]" < file1 > file2      

解密，使用原参数将file2文件解密为原文件file1
tr "[a-m][n-z]" "[n-z][a-m]" < file2 > file1

# cat test1 
hello world!
good luck!
# tr "[a-m][n-z]" "[n-z][a-m]" < test1 > test2
# cat test2
uryyb jbeyq!
tbbq yhpx!

# tr "[a-m][n-z]" "[n-z][a-m]" < test2 > test3
# cat test3
hello world!
good luck!

同理可以设置数字加密
tr "[0-4][5-9]" "[5-9][0-4]" < file1 > file2
tr "[0-4][5-9]" "[5-9][0-4]" < file2 > file1

混合加密
tr "[a-m][n-z][A-M][N-Z][0-4][5-9]" "[n-z][a-m][N-Z][A-M][5-9][0-4]" < file1 > file2
tr "[a-m][n-z][A-M][N-Z][0-4][5-9]" "[n-z][a-m][N-Z][A-M][5-9][0-4]" < file2 > file1