bash: initiate command inside of a string. - using sed

Question

my sed input is as follows:

sed 's/ListenAddress=.*/ListenAddress= $hostname/' nodemanager.properties

I am trying to run this against a Linux server and replace ListenAddress={current_value} with ListenAddress={hostname_of_server}

I need to know how to run the hostname command and have that output be reflected at the end of ListenAddress=

Thanks

Kind of, except that when I use ```sed 's/ListenAddress=.*/ListenAddress=$(hostname)/' nodemanager.properties``` in prints ListenAddress=$(hostname) — aphexlog, Nov 22 '17 at 18:16

score 0 · Answer 1 · answered Nov 22 '17 at 18:27

If you wish your bash variables to reflect inside the sed script use, double quotes. The same is valid for command substitution. So you should be doing

sed "s/ListenAddress=.*/ListenAddress= $(hostname)/" nodemanager.properties

Since thevariable expansion takes place, you need to be careful about certain situations where $ appear as a sed attribute. For example if you're applying the above command only to the last line of the file, then do

sed "\$s/ListenAddress=.*/ListenAddress= $(hostname)/" nodemanager.properties

Note the $ before s command is escaped meaning that it is literal $ supplied to the script.

bash: initiate command inside of a string. - using sed

1 Answers1