Writing the output of a command to specific columns of a csv file, unix - bash

Question

I wanted to write the output of command to specific columns (3rd and 5th) of the csv file.
#!/bin/bash
echo -e "Value,1\nCount,1" >> file.csv
echo "Header1,Header2,Path,Header4,Value,Header6" >> file.csv
sed 'y/ /,/' input.csv >> file.csv
input.csv in the above snippet will look something like this
1234567890 /training/folder
0325435287 /training/newfolder
Current output of file.csv
Value,1
Count,1
Header1,Header2,Path,Header4,Value,Header6
1234567890,/training/folder
0325435287,/training/newfolder
Expected Output of file.csv
Value,1
Count,1
Header1,Header2,Path,Header4,Value,Header6
,,/training/folder,,1234567890,
,,/training/newfolder,,0325435287,

Answer 1

All the operations can be done in a single awk:
awk -v OFS=, -v pre="Value,1\nCount,1" -v hdr="Header1,Header2,Path,Header4,Value,Header6" '
BEGIN {print pre; print hdr}
{print "", "", $1, "", $2, ""}
' input.csv
Value,1
Count,1
Header1,Header2,Path,Header4,Value,Header6
,,i1234567890,,/training/folder,
,,0325435287,,/training/newfolder,

Answer 2

With sed you could try following code. Which is using sed's capability of back reference.
sed -E 's/(^[^ ]*) +(.*$)/,,\2,,\1,/' Input_file
Explanation: Using -E option of sed to enable ERE(extended regular expressions) first. Then in main program using s option to perform substitution operation. In 1st part of substitution creating 2 back references(capability to catch values by using regex and keep them in temp buffer memory to be used later on while substituting it with in 2nd part of substitution). In 2nd part of substitution substituting whole line with 2 commas followed by 2nd capturing group\2 followed by 2 commas followed by 1st capturing group \1 following by ,.

Answer 3

You can use awk instead of sed
cat input.csv | awk '{print ",," $1 "," $2 ","}' >> file.csv
awk can process a stdin input by line to line. It implements a print function and each word is processed as a argument (in your case, $1 and $2). In the above example, I added ,, and , as an inline argument.

Answer 4

You can trivially add empty columns as part of your sed script.
sed 'y/ /,/;s/,/,,/;s/^/,,/;s/$/,/' input.csv >> file.csv
This replaces the first comma with two, then adds two up front and one at the end.
Your expected output does not look like valid CSV, though. This is also brittle in that it will fail for any file names which contain a space or a comma.