[bash]#ls
three_file  trr.sh
[bash]# cat three_file
qwert1u
[bash]# 
[bash]# cat trr.sh
#!/bin/bash

one_param='1'
two_param='A'
three_param=$(cat ./3_file)

echo $one_param
echo $two_param
echo $three_param

echo $three_param | tr $one_param $two_param
[bash]#
[bash]# sh trr.sh
1
A
qwert1u
qwertAu
[bash]# 

[bash]# sh trr.sh > result
[bash]# 
[bash]# cat result
1
A
qwert1u
qwertAu