Multi tool use

How to make search, enter text and replace a line in bash?

I've been trying to write a bash code (experimenting) where bash will ask (Enter Text) and the user will enter a certain text lets say (I am new) and the text (I am new) will be moved to a line called User=I am new.

So, here is a cfg file named xyz.cfg

User
Name
Address
Country


and here is the bash script called test and with only echo $Input > $file the bash replace the whole file with the entered text but I want to keep the config as it is and add the Enter Text: value to the line User but this doesn't help, the code below,

#! /bin/sh
file=/root/xyz.cfg
echo "Enter text:"
read Input
echo $Input > $file **(confused here)** **(it replaces the whole cfg)**


Another line I thought of is here, but it doesn't work. I am not good with these so I hope it's solved; I tried searching the web with zero luck.

(doesn't work)

#! /bin/sh
file=/root/xyz.cfg
echo "Enter text:"
read Input
echo $Input > sed '/User/a' xyz.cfg


(doesn't work)

#! /bin/sh
file=/root/xyz.cfg
echo "Enter text:"
read Input
echo $Input > sed '/User/a' $file


Edit:

When a someone is asked for Enter Text: while running the bash script ./test and the someone typed Entered Text from bash promot the entered $Input (Entered Text from bash promot) should move to xyz.cfg and add the line to the Variable User:

Finally, the xyz.cfg should look like

User: Entered Text from bash prompt
Name
Address
Country


Before it looked like this,

User:
Name
Address
Country


Edit2: This GIF might explain what I need.

1 Answer
1

This should do the trick:

#!/bin/bash
FILE=/tmp/test.cfg

echo -n "Enter text: "
read INPUT
sed -i "s/User:/& $INPUT/" "$FILE"


This uses sed to do an in-place search / replace (-i) which appends the entered text after the first occurence of User: on each line within $FILE.

-i

User:

$FILE

& refers to the matched portion of the text - it's essentially saying "replace <thing> with <thing> <entered text>."

&

<thing>

<thing> <entered text>

If you need to prompt for text each time a matching User: line is encountered, you can use the following approach:

User:

#!/bin/bash
FILE=/tmp/test.cfg
ORIGINAL=$(cat "$FILE")

truncate -s 0 "$FILE"
while read LINE; do
if `grep -q 'User:' <<< "$LINE"`; then
echo -n "Enter text: "
read INPUT < /dev/tty
sed "s/User:/& $INPUT/" <<< "$LINE" >> "$FILE"
else
echo "$LINE" >> "$FILE"
fi
done <<< "$ORIGINAL"


This second approach does the following:

User:

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