sed not working in shell script

Question

I am fairly new to sed and am trying to use sed to insert a user inputed line as the first line in another text file. The shell script I am try to use is:

echo -n "Enter values: "
read text
echo "You entered: $text"

sed  -i '1i $text' $file

The return I get is:

"sed: -i may not be used with stdin"

Are you sure `$file` is not empty? Also, `$text` in single quotes doesn't expand. — choroba, Oct 27 '16 at 22:44
ah yes for some reason $file was empty. It did not pass from the previous script. I changed file to a direct file name and got "sed: 1: "new.txt": extra characters at the end of n command" — Steven Somach, Oct 27 '16 at 23:03
Sounds like the `1i $text` was interpreted as the value of the `-i` option. — choroba, Oct 27 '16 at 23:07
am I using improper syntax or something that is causing that? — Steven Somach, Oct 27 '16 at 23:49

score 0 · Answer 1 · answered Nov 07 '16 at 00:46

I made this example.sh :

#!/bin/bash
file="new.txt"
echo>$file # the file must not be empty, as sed needs a stream to work with
echo -n "Enter values: "
read text
echo "You entered: $text"
sed -i "\$a$text" $file

Explanation :

The escaped $ refers to the last line, and a is the command to append.
I guess you're trying to learn sed, but obviously you should prefer echo with >> instead.

sed not working in shell script

1 Answers1