Creating an output file with multi line script using echo / linux

Question

Trying to create a small script capable to write a part off the script in the output file without any changes, (as is)

source file text

echo "
yellow=`tput setaf 3`
bel=`tput bel`
red=`tput setaf 1`
green=`tput setaf 2`
reset=`tput sgr0
echo"#${green}Installing packages${reset}#" &&
" >> output.txt

Desired output:

yellow=`tput setaf 3`
bel=`tput bel`
red=`tput setaf 1`
green=`tput setaf 2`
reset=`tput sgr0
echo"#${green}Installing packages${reset}#" &&

What I'm getting is:

yellow=^[[33m
bel=^G
red=^[[31m
green=^[[32m
reset=^[(B^[[m
echo"#${green}Installing packages${reset}#" &&

Using CentOS 7 Minimal fresh install Looking for a solution to be applied to the full script/text, no the line per line changes, I suppose may be done using sed too ...

Solution 1

You need to escape the backticks (`):

#!/bin/bash
echo "
yellow=\`tput setaf 3\`
bel=\`tput bel\`
red=\`tput setaf 1\`
green=\`tput setaf 2\`
reset=\`tput sgr0\`
" >> output.txt

As a bonus:

I prefer using this method for multiline:

#!/bin/bash
cat << 'EOF' >> output.txt
yellow=$(tput setaf 3)
bel=$(tput bel)
red=$(tput setaf 1)
green=$(tput setaf 2)
reset=$(tput sgr0)
EOF

Solution 2

Use single quote to prevent expansions:

echo '
yellow=`tput setaf 3`
bel=`tput bel`
red=`tput setaf 1`
green=`tput setaf 2`
reset=`tput sgr0`
' >> output.txt

For more details see Difference between double and single quote.

---

If your text includes single quote then the above may not work. In that case using a here doc would be safer. For example, the above will break if you insert a line: var='something'.

Using a here doc it will be like this:

cat >> output.txt <<'EOF'
yellow=`tput setaf 3`
bel=`tput bel`
red=`tput setaf 1`
green=`tput setaf 2`
reset=`tput sgr0`
var='something'
EOF

Solution 3

Just a late addition:

The echo 'string' >> output command is simple and great. But it may will give you the '...: Permission denied' error combined with sudo.

I recently had a lil issue with sudo echo 'string \n other string \n' > /path/to/file

What worked for me the best:
printf "Line1\nLine2\nLine3" | sudo tee --append /path/to/file

It's an extra that you actually have the string printed to the stdout too, so you will see what was written to the file.