How do I replace a string with a newline using a bash script and sed?

Question

I have the following input:

Value1|Value2|Value3|Value4@@ Value5|Value6|Value7|Value8@@ Value9|etc...

In my bash script I would like to replace the @@ with a newline. I have tried various things with sed but I'm not having any luck:

line=$(echo ${x} | sed -e $'s/@@ /\\\n/g')

Ultimately I need to parse this whole input into rows and values. Maybe I am going about it wrong. I was planning to replace the @@ with newlines and then loop through the input with setting IFS='|' to split up the values. If there is a better way please tell me, I am still a beginner with shell scripting.

Answer 1

Using pure BASH string manipulation:

eol=$'\n'
line="${line//@@ /$eol}"

echo "$line"
Value1|Value2|Value3|Value4
Value5|Value6|Value7|Value8
Value9|etc...

Or else do it in single step:

line="${line//@@ /$'\n'}"

Answer 2

This will work

sed 's/@@ /\n/g' filename

replaces @@ with new line

Answer 3

I recommend using the tr function

echo "$line" | tr '@@' '\n'

For example:

[itzhaki@local ~]$ X="Value1|Value2|Value3|Value4@@ Value5|Value6|Value7|Value8@@"
[itzhaki@local ~]$ X=`echo "$X" | tr '@@' '\n'`
[itzhaki@local ~]$ echo "$X"
Value1|Value2|Value3|Value4

 Value5|Value6|Value7|Value8

Answer 4

Finally got it working with:

sed 's/@@ /'\\\n'/g'

Adding the single quotes around \\n seemed to help for whatever reason

Answer 5

If you don't mind to use perl:

echo $line | perl -pe 's/@@/\n/g'
Value1|Value2|Value3|Value4
 Value5|Value6|Value7|Value8
 Value9|etc

Answer 6

How about:

for line in `echo $longline | sed 's/@@/\n/g'` ; do
    $operation1 $line
    $operation2 $line
    ...
    $operationN $line
    for field in `echo $each | sed 's/|/\n/g'` ; do
        $operationF1 $field
        $operationF2 $field
        ...
        $operationFN $field
    done
done

Answer 7

This wraps up using perl to do it, and gives some simple help.

$ echo "hi\nthere"
hi
there

$ echo "hi\nthere" | replace_string.sh e
hi
th
re

$ echo "hi\nthere" | replace_string.sh hi


there

$ echo "hi\nthere" | replace_string.sh hi bye
bye
there

$ echo "hi\nthere" | replace_string.sh e super all
hi
thsuperrsuper

replace_string.sh

#!/bin/bash

ME=$(basename $0)
function show_help()
{
  IT=$(cat <<EOF

  replaces a string with a new line, or any other string, 
  first occurrence by default, globally if "all" passed in

  usage: $ME SEARCH_FOR {REPLACE_WITH} {ALL}

  e.g. 

  $ME :       -> replaces first instance of ":" with a new line
  $ME : b     -> replaces first instance of ":" with "b"
  $ME a b all -> replaces ALL instances of "a" with "b"
  )
  echo "$IT"
  exit
}

if [ "$1" == "help" ]
then
  show_help
fi
if [ -z "$1" ]
then
  show_help
fi

STRING="$1"
TIMES=${3:-""}
WITH=${2:-"\n"}

if [ "$TIMES" == "all" ]
then
  TIMES="g"
else
  TIMES=""
fi

perl -pe "s/$STRING/$WITH/$TIMES"