Bash/perl function to search `lsblk` for drives whose partitions all match a filter

Question

The following function searches for disks whose partitions all have an attribute that match a filter when listed with lsblk. Comments are in TomDoc format.

# Public: finds drives in /dev/sd* whose partitions all have an attribute that matches a filter.
# 
# $1 - filter (default: '.*')
# $2 - attribute (default: 'MOUNTPOINT')
#
# Returns full paths to disks whose attributes match the filter
#
# Examples
#  lsblk /dev/sda -oTYPE,PATH,MOUNTPOINTS --pairs
#   #  TYPE="disk" PATH="/dev/sda" MOUNTPOINTS=""
#   #  TYPE="part" PATH="/dev/sda1" MOUNTPOINTS="/boot/efi"
#   #  TYPE="part" PATH="/dev/sda2" MOUNTPOINTS="/var/snap/firefox/common/host-hunspell\x0a/"
#  lsblk_disk_filter '(/var/snap/firefox/common/host-hunspell\\x0a/|/boot/efi)' 'MOUNTPOINTS'
#   #  /dev/sda
#
#  lsblk /dev/sda -oTYPE,PATH,FSTYPE --pairs
#   # TYPE="disk" PATH="/dev/sda" FSTYPE=""
#   # TYPE="part" PATH="/dev/sda1" FSTYPE="vfat"
#   # TYPE="part" PATH="/dev/sda2" FSTYPE="ext4"
#  lsblk_disk_filter '(ext4|xfs|vfat)' 'FSTYPE'
#   # /dev/sda
# 
# REQUIRES lsblk >= 2.33 for PATH output option - https://github.com/util-linux/util-linux/blob/master/Documentation/releases/v2.33-ReleaseNotes#L372
# TODO: add support for /dev/nvme* (I don't have hardware to test this...)
lsblk_disk_filter () {
  local filter="${1:-'.*'}";
  local attribute="${2:-'MOUNTPOINT'}"

  local PERLCMD='my ($type, $path, $attr) = /^TYPE\="([^"]*)"\s*PATH\="([^"]*)"\s*$col\="([^"]*)"\s*$/ or next; # VAR ASSIGNMENT \
  if( $type=~/disk/i){          # CHECK IF TYPE IS DISK \
    printf("%s ",$disk);          # PRINTING LAST DISK \
    $disk=$path;                 # ASSIGN NEXT DISK \
  } elsif($attr!~/$filter/){    # PARTITION ATTRIBUTE MISMATCH TEST \
    $disk="";                   # DELETING DISK ON MISMATCH \
  } END{ printf($disk); } # PRINT LAST DISK'

  lsblk --pairs --noheadings --ascii -o TYPE,PATH,$attribute /dev/sd* | perl -s -wnl -E "${PERLCMD}" -- -filter="$filter" -disk='' -col=$attribute
  # perl switch example: https://stackoverflow.com/questions/31155659/how-do-i-pass-command-line-options-to-a-perl-program-with-perl-e
  # /dev/sdx describes SCSI/SATA devices, /dev/sdx\d+ describes their partitions.
  # See the /dev/ naming convention described in the "devices" section in fdisk.
} # END lsblk_disk_filter

Answer 1

Given that the majority of this is Perl, it's probably worth using Perl as the main interpreter and using that to invoke lsblk directly.

Alternatively, use shell more, and consider using JSON output and jq for the parsing. That might fix the bug that we don't correctly parse anything which lsblk prints using hex escapes.

We're not using a tree display from lsblk, so the --ascii option is redundant.

---

As a starting point for using jq, this simple program finds the disks:

lsblk --json --noheadings -O |
  jq '.blockdevices[]|select(.type=="disk")|.path'

It shouldn't be hard to extend this to add additional selectors to the select() call.