AWK formatting Disk Utility command formatting incorrectly

Question

I am trying to learn awk at the moment and so I am trying it on the disk utility command.

Here is the output when I run Disk Utility list disk0

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            145.4 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
   4:           Linux Filesystem                         48.0 GB    disk0s4
   5:       Microsoft Basic Data WINDOWS                 38.0 GB    disk0s5
   6:                 Linux Swap                         18.8 GB    disk0s6

Now if I run diskutil list disk0 | awk 'NR > 2 {print}' I get this as my output.

   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            145.4 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
   4:           Linux Filesystem                         48.0 GB    disk0s4
   5:       Microsoft Basic Data WINDOWS                 38.0 GB    disk0s5
   6:                 Linux Swap                         18.8 GB    disk0s6

As you can see the output is as expected. The issue now is when I try printing $2,$3 and $4, The output sometimes prints 'HD' when it should print the size and other issues like this.

diskutil list disk0 | awk 'NR > 2 {print $1}'

0:
1:
2:
3:
4:
5:
6:

Expected result

diskutil list disk0 | awk 'NR > 2 {print $2}'

GUID_partition_scheme
EFI
Apple_HFS
Apple_Boot
Linux
Microsoft
Linux

Expected result

GUID_partition_scheme
EFI
Apple_HFS
Apple_Boot
Linux Filesystem
Microsoft Basic Data
Linux Swap

As you can see the command outputs as expected until the Linux Filesystem. This is due to there being spaces in the word?

This now affects everything else that comes after it, for example

diskutil list disk0 | awk 'NR > 2 {print $3}' displays

*251.0
EFI
Macintosh
Recovery
Filesystem
Basic
Swap

when it should show

EFI
Macintosh HD
Recovery HD

Windows

How would I get AWK to format as I would expect?

Answer 1

diskutil output is formatted with multiple spaces to output in neat columns. Extract the fields required using awk's substr function.

For example to extract the type and name from diskutil. The substr functions extract the fields from the diskutil output. For example, the name field begins at position 6 and is up to 27 chars long. The gsub functions merely strip leading and trailing white space from the fields.

diskutil list disk0 | awk 'NR > 2 {
   name=substr($0, 33,20);  # name field - position 33, length 20 chars
   gsub(/ /,"",name)    # trim spacing

   type=substr($0, 6, 27);  # type field - position 6, length 27 chars
   gsub(/ /,"",type)    # trim spacing
   print "name="name," type="type
}' 

Answer 2

With bash you can do:

diskutil list disk0 | { read; read; while read i; do echo ${i:6:27}; done; }

• The first two reads are to ignore the first to lines.
• The while loop reads the input line by line and prints the desired part.

Edit: If it must be awk, use this:

diskutil list disk0 | awk 'NR>2{$0=substr($0,6,27);sub("^ +","",$0);print}'

• NR>2 omits the first two line in the output
• substr() cuts the relevat part
• sub() removes the leading spaces
• and finally print prints the line