professorswag123 professorswag123 - 1 month ago 14
Bash Question

Linux sed command - using variable with backslash

I'm trying to replace a string in a file. i have to use a variable since i have to do this in alot of lines. how do i escape the backslash?

text.txt:

1234567#Hello World#Hello I\u0027m Scott


script:

#!/bin/bash
FOLDERID=`cat text.txt | cut -d# -f1` # example: 12345
oldstring=`cat text.txt | cut -d# -f2` # example: "Hello World"
newstring=`cat text.txt | cut -d# -f3` # example: "Hello I\u0027m Scott"
sed -i "s/${oldstring}/${newstring}/g" $FOLDERID/myfile.txt


cat myfile.txt after sed

Hello I0027m Scott


how can i escape a backslash? i only know how to escape slashes which would work like:

newstring=Hello I/u0027m Scott
newstring=${newstring//\//\\\/}
echo ${newstring} # => Hello I\/u0027m Scott

Answer

Try this:

cd /tmp
mkdir -p 1234567
echo Hello World >1234567/myfile.txt
echo '1234567#Hello World#Hello I\u0027m Scott' >text.txt

Well, then:

IFS=\# read -r FOLDERID oldstring newstring <text.txt 
sed "s/${oldstring}/${newstring//\\/\\\\}/g" -i $FOLDERID/myfile.txt
cat 1234567/myfile.txt 
Hello I\u0027m Scott