Issue
I have written the following command
#!/bin/bash
awk -v value=$newvalue -v row=$rownum -v col=1 'BEGIN{FS=OFS=","} NR==row {$col=value}1' "${file}".csv >> temp.csv && mv temp.csv "${file}".csv
Sample Input of file.csv
Header,1
Field1,Field2,Field3
1,ABC,4567
2,XYZ,7890
Assuiming $newvalue
=3 ,$rownum
=4 and col
=1, then the above code will replace:
Required Output
Header,1
Field1,Field2,Field3
1,ABC,4567
3,XYZ,7890
So if I know the row and column, is it possible to replace the said value using grep, sed?
Edit1: Field3 will always have a unique value for their respective rows. ( in case that info helps anyway)
Solution
Assuming your CSV file is as simple as what you show (no commas in quoted fields), and your newvalue
does not contain characters that sed would interpret in a special way (e.g. ampersands, slashes or backslashes), the following should work with just sed (tested with GNU sed):
sed -Ei "$rownum s/[^,]*/$newvalue/$col" file.csv
Demo:
$ cat file.csv
Header,1
Field1,Field2,Field3
1,ABC,4567
3,XYZ,7890
$ rownum=3
$ col=2
$ newvalue="NEW"
$ sed -Ei "$rownum s/[^,]*/$newvalue/$col" file.csv
$ cat file.csv
Header,1
Field1,Field2,Field3
1,NEW,4567
3,XYZ,7890
Explanations: $rownum
is used as the address (here the line number) where to apply the following command. s
is the sed substitute command. [^,]*
is the regular expression to search for and replace: the longest possible string not containing a comma. $newvalue
is the replacement string. $col
is the occurrence to replace.
If newvalue
may contain ampersands, slashes or backslashes we must sanitize it first:
sanitizednewvalue=$(sed -E 's/([/\&])/\\\1/g' <<< "$newvalue")
sed -Ei "$rownum s/[^,]*/$sanitizednewvalue/$col" file.csv
Demo:
$ newvalue='NEW&\/&NEW'
$ sanitizednewvalue=$(sed -E 's/([/\&])/\\\1/g' <<< "$newvalue")
$ echo "$sanitizednewvalue"
NEW\&\\\/\&NEW
$ sed -Ei "$rownum s/[^,]*/$sanitizednewvalue/$col" file.csv
$ cat file.csv
Header,1
Field1,Field2,Field3
1,NEW&\/&NEW,4567
3,XYZ,7890
Answered By - Renaud Pacalet Answer Checked By - Mildred Charles (WPSolving Admin)