unix command extract field from text file

Question

I have a text file delimited by | (multiple records).

field1|field2|field3|field4|field5

i wanted to check if field3 is blank or contains "space" characters only, if it is blank or space, i wanted the whole line to show up.

what unix command can i use to do this ?

Michael

Answer 1

$ echo "1|2||4" | awk -F'|' '$3 ~ /^[ \t]*$/ {print $0}'

1|2||4

$ echo "1|2| |4" | awk -F'|' '$3 ~ /^[ \t]*$/ {print $0}'

1|2| |4

$ echo "1|2| 3|4" | awk -F'|' '$3 ~ /^[ \t]*$/ {print $0}'

Answer 2

You can also use the cut command to pull out the third field and then test the value:

$ echo "field1|field2|field3|field4|field5" | cut -d '|' -f 3
field3

Answer 3

My random attempt using grep would be:

grep -E '^[^|]*\|[^|]*\| *[^| ]+ *\|' file

Answer 4

I'm not certain about unix, but in linux you would want to use the sed command.

sed 's/||/\n/g' will make it so that if there are any blank fields it will add a new line. not certain how to get it to only check the 3rd field. sed 's/| |/\n/g' should work for only spaces.