envsubst sh$ cat << EOF > hello.txt hello $USER EOF $ cat hello.txt hello $USER $ USER=deptno envsubst < hello.txt hello deptno $ cat hello.txt | USER=deptno envsubst hello deptnolink
$ cat << EOF > hello.txt hello $USER EOF $ cat hello.txt hello $USER $ USER=deptno envsubst < hello.txt hello deptno $ cat hello.txt | USER=deptno envsubst hello deptno