how to insert backslash at the front of # symbol? In bash programming, given a variable, say `varA`, that store a string containing `#` symbol. Let's assume `varA` contain this value: `ASD# 1`, I need to append a backslash `\` at the front of `#`, so the output could have this: `ASD\# 1`. The following code is about there to achieve my objective, just that the string replacement doesn't seem to work and I'm not able to assign the output from sed command into another variable. Any sight on this? varA="ASD# 1" echo $(sed s/\#/\\#/g <<< ${varA})

You missing quote in your `sed` expression.

Try:


$ varA="ASD# 1"
$ echo "$(sed 's/#/\\#/g' <<< "${varA}")"
ASD\# 1