[J65nko]

An example of an OpenBSD /etc/fstab file:

/dev/wd0a / ffs rw 1 1
/dev/wd0m /backup ffs rw,nodev,nosuid 1 2
/dev/wd0e /home/j65nko ffs rw,nodev,nosuid 1 2
/dev/wd0d /tmp ffs rw,nodev,nosuid 1 2
/dev/wd0k /usr ffs rw,nodev 1 2
/dev/wd0l /usr/local ffs rw,nodev 1 2
/dev/wd0f /var ffs rw,nodev,nosuid 1 2
/dev/wd0h /var/log ffs rw,nodev,nosuid 1 2
/dev/wd0g /var/tmp ffs rw,nodev,nosuid 1 2

A nicely formatted version:

# special       mount                                   fs      mount                                   dump    fsck
# device        point                                   type    options                                 freq    pass#
# =======       =====                                   ====    =======                                 ====    =====
#
/dev/wd0a       /                                       ffs     rw                                      1       1
/dev/wd0m       /backup                                 ffs     rw,nodev,nosuid                         1       2
/dev/wd0e       /home/j65nko                            ffs     rw,nodev,nosuid                         1       2
/dev/wd0d       /tmp                                    ffs     rw,nodev,nosuid                         1       2
/dev/wd0k       /usr                                    ffs     rw,nodev                                1       2
/dev/wd0l       /usr/local                              ffs     rw,nodev                                1       2
/dev/wd0f       /var                                    ffs     rw,nodev,nosuid                         1       2
/dev/wd0h       /var/log                                ffs     rw,nodev,nosuid                         1       2
/dev/wd0g       /var/tmp                                ffs     rw,nodev,nosuid                         1       2

The awk script to accomplish this:

# Reformat OpenBSD /etc/fstab file 
# $Id: format_fstab,v 1.1 2010/01/27 02:14:02 j65nko Exp $
# usage:  awk -f format_fstab /etc/fstab

# WARNING: first backup your original fstab file before redirecting
#          the output of this awk script to the /etc/fstab
#  cd /etc
#  cp -p fstab fstab.orig 
#  awk -f format_fstab fstab.orig >fstab
#  cat fstab
 

BEGIN {
    printf("%s\t%s\t\t\t\t\t%s\t%s\t\t\t\t\t%s\t%s\n", "# special","mount","fs","mount","dump","fsck")
    printf("%s\t%s\t\t\t\t\t%s\t%s\t\t\t\t\t%s\t%s\n","# device","point","type","options","freq","pass#")
    printf("%s\t%s\t\t\t\t\t%s\t%s\t\t\t\t\t%s\t%s\n","# =======","=====","====","=======","====","=====")
    printf("#\n")
}

{
    T2=" "
    if (length($2) >= 1 )  T2="\t\t\t\t" 
    if (length($2) >= 8 )  T2="\t\t\t" 
    if (length($2) >= 16 ) T2="\t\t"
    if (length($2) >= 24 ) T2="\t"

    T4=" "
    if (length($4) >= 1 )  T4="\t\t\t\t" 
    if (length($4) >= 8 )  T4="\t\t\t" 
    if (length($4) >= 16 ) T4="\t\t"
    if (length($4) >= 24 ) T4="\t"

    printf( "%s\t%s%s\t%s\t%s%s\t%s\t%s\n" ,$1,$2,T2,$3,$4,T4,$5,$6) 
}
# end of script

The previous version :

# --------------------------------------------------

FILE=/etc/fstab
FILE=./fstab

ORIG=${FILE}.orig

cp ${FILE} ${ORIG}      # create backup

echo Formatting ${FILE}

cat <<END >${FILE}
# special       mount           fs      mount                           dump    fsck
# device        point           type    options                         freq    pass# 
# ======        =====           ====    =======                         ====    =====
#
$(awk '{ printf("%s\t%s\t\t%s\t%s\t\t\t\t%s\t%s\n", $1, $2, $3, $4, $5, $6)}' $ORIG )
/dev/cd0a       /cdrom          d9660   ro,noauto                       0       0
/dev/fd0a       /floppy         msdos   ro,noauto                       0       0
END

cat $FILE