How To Reverse a String In Unix / Linux Shell?

To reverse a string in a Unix or Linux shell, you can use the rev command. This command reads a string from standard input and writes the reverse of the string to standard output.

Here is an example of how to use the rev command to reverse a string:

echo "Hello World" | rev

This will output the string "dlroW olleH".

You can also use the rev command in combination with the echo command to reverse the contents of a variable. For example:

mystring="Hello World"
echo "${mystring}" | rev

This will output the string "dlroW olleH".

Alternatively, you can use the sed command to reverse a string. For example:

echo "Hello World" | sed 's/.*/&/;s/\(.\)/\1\n/g' | tac | tr -d '\n'

This will output the string "dlroW olleH".

You can also use the awk command to reverse a string. For example:

echo "Hello World" | awk '{for (i=length; i>0; i--) printf "%s",substr($0, i, 1); print ""}'

This will output the string "dlroW olleH".

Keep in mind that these methods will only work if the string is relatively short. If the string is longer, it may be more efficient to use a different method to reverse the string.