Explanation:

I want to change "/dev/dsk/c0t0d0s1" into "/dev/md/dsk/d1" and "/dev/rdsk/c0t0d0s1" into "/dev/md/rdsk/d1" for each line containing those in the file.

Command Line:

sed -e 's/\/dev\/dsk/\/dev\/md\/dsk/' vfstab |sed -e 's/\/dev\/rdsk/\/dev\/md\/rdsk/' |sed -e 's/c[0-9]t[0-9]d[0-9]s/d/g'

File:

#device         device          mount           FS      fsck    mount   mount
#to mount       to fsck         point           type    pass    at boot options
#
fd      -       /dev/fd fd      -       no      -
/proc   -       /proc   proc    -       no      -
/dev/dsk/c0t0d0s1       -       -       swap    -       no      -
/dev/dsk/c0t0d0s0       /dev/rdsk/c0t0d0s0      /       ufs     1       no -
/dev/dsk/c0t0d0s3       /dev/rdsk/c0t0d0s3      /var    ufs     1       no -
/dev/dsk/c0t0d0s6       /dev/rdsk/c0t0d0s6      /export ufs     2       yes -
/dev/dsk/c0t0d0s7       /dev/rdsk/c0t0d0s7      /export/free    ufs     2 yes     -
/dev/dsk/c0t0d0s5       /dev/rdsk/c0t0d0s5      /opt    ufs     2       yes -
swap    -       /tmp    tmpfs   -       yes     -