Can I use sed to manipulate a variable in bash?

问题:

In my program, I would like to first get the user input, and insert a \ before each / so I write this, but it doesn't work.

echo "input a website"
read website

sed '/\//i\/' $website

回答1:

Try this:

website=$(sed 's|/|\\/|g' <<< $website)

Bash actually supports this sort of replacement natively:

${parameter/pattern/string} — replace the first match of pattern with string.
${parameter//pattern/string} — replace all matches of pattern with string.

Therefore you can do:

website=${website////\\/}

Explanation:

website=${website // / / \\/}
                  ^  ^ ^  ^
                  |  | |  |
                  |  | |  string, '\' needs to be backslashed
                  |  | delimiter
                  |  pattern
                  replace globally

回答2:

echo $website | sed 's/\//\\\//g'

or, for better readability:

echo $website | sed 's|/|\\/|g'