Replace column values in a CSV file with awk
awk, compare, csv, text, zero
Solution
awk -F ',' -v OFS=',' '$1 { if ($3=="") $3="No value"; print}' in.txt
- Passes the field separator via the `-F` option.
- Variable `OFS`, the output-field separator, is set to `,`, so that output fields are also separated by `,`.
- Pattern `$1` ensures that only non-empty lines are processed (that is, the associated action is only executed if the first field is non-empty) - if your input file has no empty lines, you can remove this pattern.
- If the 3rd field is empty, it is assigned string "No value"
- Finally, the line (with the potentially modified 3rd field) is output.
The above is how I suggest you approach the problem, but here are the problems with your original command:
- `{{FS=","}...` Inside your single action - which due to not having a preceding pattern is executed for every input line - you set variable `FS` for every line - which is not only unnecessary but too late, because the first input line has already been parsed by that time (thanks, @EdMorton) - either set it in a `BEGIN` block (`BEGIN { FS="," }`) or, as in my answer, with command-line option `-F` (`-F ','`).
- `if($3=="") {...}` You only produce output if field `$3` is empty - presumably, though, you want to output all lines, so with this approach you'd need an `else` branch (to print unmodified lines).
- `print $1,$2,"No value"` The `,` chars. here are part of the syntax - they simply separate the arguments passed to `print`. Given separate arguments, `print` concatenates them with the value of the special `OFS` variable, whose value is a single space by default; to use `,` instead, you have to assign it to `OFS` - again, either in a `BEGIN` block or via the `-v` option (`-v OFS=','`).
Problem
I have this file error.log [00:00:00.284],501, [00:00:00.417],5,5294100071980 [00:00:02.463],501, [00:00:05.169],501, [00:00:05.529],501, [00:00:05.730],501, so, if the field $3 its empty i want to print "No value" Im trying this code ``` awk '{{FS=","} if($3=="") {print $1,$2,"No value"}}' ``` But it prints ``` >[00:00:00.284] 501 No value >[00:00:02.463] 501 No value >[00:00:05.169] 501 No value >[00:00:05.529] 501 No value >[00:00:05.730] 501 No value >[00:00:07.193] 501 No value >[00:00:09.899] 501 No value >[00:00:31.312] 501 No value ```