To find and replace values in specific fields using the awk command, you can use the sub or gsub functions. The sub function allows you to replace the first occurrence of a specified string in a field, while the gsub function allows you to replace all occurrences of a string in a field.
For example, to replace the first occurrence of the string "oldstring" with the string "newstring" in the second field of a file, you could use the following awk command:
awk '{sub("oldstring", "newstring", $2); print}' filename
This will find the first occurrence of "oldstring" in the second field of each line of the filename file, and replace it with "newstring". The updated line will then be printed to the terminal.
To replace all occurrences of "oldstring" with "newstring" in the second field of a file, you could use the following awk command:
awk '{gsub("oldstring", "newstring", $2); print}' filename
This will find all occurrences of "oldstring" in the second field of each line of the filename file, and replace them with "newstring". The updated line will then be printed to the terminal.