Cannot translate specific characters with tr utility

Suppose I have a file named doc with content:

{}
[]

Now I want to translate all the '{' and '[' into '(' and '}' and ']' into ')'. So far, I can translate '{}' and '[' correctly, but I can't tra开发者_StackOverflownslate ']', using this shell command:

cat doc | tr [\[] [\(] | tr [\{] [\(] | tr [\}] [\)] | tr [\]] [\)] | cat

The output is:

()
(]

So far, it can translate other character, except for ']'. Do you know why?

This is a shell exercise, which asks to translate all '{}' and '[]' in a .c file into '()'. I just want to simply it here.

tr just takes character sets and ranges - you don't need to surround them with [] like regular expression ranges. You can do all your translations with a single command:

echo 'hello [ world }' | tr '[]{}' '()()' 

Here's one example that works fine:

echo '{}' |tr '\{\}' '\[\]'

OUTPUT: []

Here's another example:

 echo '}' | tr \} \]

OUTPUT: ]