Command to escape a string in bash

Question

I need a bash command that will convert a string to something that is escaped. Here's an example:

echo "hello\world"|escape|someprog

Where the escape command makes "hello\world" into "hello\\world". Then, someprog can use "hello\world" as it expects. Of course, this is a simplified example of what I will really be doing.

Answer 1

You can use perl to replace various characters, for example:

$ echo "Hello\ world" | perl -pe 's/\\/\\\\/g'
Hello\\ world

Depending on the nature of your escape, you can chain multiple calls to escape the proper characters.

Answer 2

Pure Bash, use parameter substitution:

string="Hello\ world"
echo ${string//\\/\\\\} | someprog

Answer 3

In Bash:

printf "%q" "hello\world" | someprog

for example:

$ printf "%q" "hello\world"
hello\\world