sed: How to delete lines matching a pattern that contains forward slashes?

Question

Suppose a file /etc/fstab contains the following:

/dev/xvda1 / ext4 defaults 1 1
/dev/md0    /mnt/ibsraid    xfs defaults,noatime    0   2
/mnt/ibsr         


        

Answer 1

You were very close. When you use a nonstandard character for a pattern delimiter, such as |pattern|, the first use of that character must be escaped:

$ sed '\|^/dev/xvdb|d' /etc/fstab
/dev/xvda1 / ext4 defaults 1 1
/dev/md0    /mnt/ibsraid    xfs defaults,noatime    0   2
/mnt/ibsraid/varlog /var/log    none    bind    0   0

Similarly, one can use:

sed '\?^/dev/xvdb?d' /etc/fstab

Lastly, it is possible to use slashes inside of /pattern/ if they are escaped in the way that you showed in your answer.