echo the cat content into a file

Question

I have file "setting.xml" which contains some environment variable

<localRepository>/Users/$(whoami)/.m2/repository

I want to write the content of setting.xml into production.xml and replace the $(whomai) with my userid

I tried below

cat setting.xml | echo > production.xml

but not sure how can I pass the content to my echo command

Answer 1

You can try:

sed "s/\$(whoami)/$(whoami)/" < setting.xml >production.xml

The sed is an stream editor, and in the above, replaces the literal $(whoami) with the result of the command whoami.

Answer 2

cat setting.xml > production.xml && sed -i "s/::whoami/$(whoami)/g"  production.xm

Just redirect cat command output with > it is better to use ::whoami in your file instead of $(whoami)

Template:

<localRepository>/Users/::whoami/.m2/repository

Answer 3

The generic approach would be :

eval echo `cat setting.xml | sed -r 's/([<>])/\\\\\1/g'` > production.xml

It may need to escape more characters than just < and >

But beware of security issues like @jm666 explained

Answer 4

To replace environment variables you can use envsubst. The entire command would be:

envsubst < setting.xml > production.xml

You can find this command in gettext package. If your system don't have it installed and you are using Ubuntu, just type:

apt-get install gettext-base

You can check envsubst manual to know more.