shell - With Sed how can I replace a random word without removing data on the same line -

i trying use sed replace string has randomly generated alphanumeric. prefixed fixed word special characters in it.

{abcd}randomalphanumric 

i can replace {abcd}, don't know how replace random alphanumeric without removing other words or data on same line. able accomplish need following sed command, doesn't seem safe command use in cases. there cleaner way this?

sed -e 's/{abcd}.........../new_myvar/g' 

this delete strings start {abcd} followed number of alphanumeric character:

 sed -e 's/{abcd}[[:alnum:]]*/new_myvar/g' 

[[:alnum:]] matches alphanumeric character , [[:alnum:]]* matches 0 or more of such characters. because sed greedy, match many alphanumeric characters possible.

example

consider test file:

$ cat file {abcd}randomalphanumric begin {abcd}adfcvr1243c end 

then, our output is:

$ sed -e 's/{abcd}[[:alnum:]]*/new_myvar/g' file new_myvar begin new_myvar end