SED Escape in bash script - bash

Question

My tempfile.txt has below contents [Typical Cisco Configuration File]
interface GigabitEthernet1/11
no ip address
shutdown
rmon collection stats 6010 owner monitor
!
interface GigabitEthernet1/12
no ip address
shutdown
rmon collection stats 6011 owner monitor
!
interface GigabitEthernet1/13
no ip address
shutdown
rmon collection stats 6012 owner monitor
!
interface GigabitEthernet1/14
no ip address
shutdown
rmon collection stats 6013 owner monitor
!
I am trying to loop through to do some operation on each block
Example
interface GigabitEthernet1/14 --> start of interface block
no ip address
shutdown
rmon collection stats 6013 owner monitor
! --> end of interface block
I have another file which has below data intefaces.txt
interface GigabitEthernet1/11
interface GigabitEthernet1/12
interface GigabitEthernet1/13
interface GigabitEthernet1/14
Now want to do some changes in each block thats why I am trying to access block in loop via
while read line
do
sed -n '/$line/,/!/p' tempfile.txt # this should get me block
#code for doing some changes in block
done < interfaces.txt
Now since my $line will be one of line of interfaces.txt eg: interface GigabitEthernet1/11
how can I escape / as I am doing in loop & my interfaces will always contain / character

Answer 1

Tell sed which character to use in place of / in the search by prefixing it with a backslash:
sed -n "\#${line}#,/!/p" ...

Answer 2

To work with block of text, use gnu awk (due to multiple characters in RS)
awk -vRS="interface" '/1\/13/ {print RS $0}' file
interface GigabitEthernet1/13
no ip address
shutdown
rmon collection stats 6012 owner monitor
!
Here you get all of info for interface 1/13
You can prevent the escaping of / by getting it in as a variable.
awk -vRS="interface" -vtest="1/13" '$0~test {print RS $0}'
interface GigabitEthernet1/13
no ip address
shutdown
rmon collection stats 6012 owner monitor
!

Answer 3

In bash, you can use the parameter global replace operator, ${varname//old/new}, to replace the slashes with backslashed slashes, like this:
while read line; do
sed -n "/${line//\//\/\/}/",'/!/p' tempfile.txt | # do stuff
done <interfaces.txt
... but Holy Leaning Toothpicks, Batman! I would go with #JonathanLeffler's solution of changing sed's search delimiter.