Question

I searched and found “echo -n” and “printf” are solution for this, but they are working a bit quirky on my machines.

here:

[wadhwaso@nxnixd01 ~]$ echo "hello" >> test
[wadhwaso@nxnixd01 ~]$ cat test
hello
[wadhwaso@nxnixd01 ~]$ echo -n "world" >> test
[wadhwaso@nxnixd01 ~]$ cat test
hello
world
[wadhwaso@nxnixd01 ~]$ echo -n " seriously?" >> test
[wadhwaso@nxnixd01 ~]$ cat test
hello
world seriously?

same is the case with “printf”. It works 2nd 3rd 4th time and so on but not the first time.

I am not very comfortable with awk and sed, thats why I wanted to use these.

If I dont have any choice can someone tell me how to add “elevator=noop” in /etc/grub.conf via awk or sed ??

Answer:
sed -i '$s/$/,string/' file ..

Answer 1

The -n option controls whether a newline is added at the end of the echo. That very first echo "hello" writes hello\n to the file; that’s where the newline is coming from.

To add a kernel option try one of these. Each of them searches for the kernel line in grub.conf and appends ” elevator=noop” to the end.

sed '/kernel/ s/$/ elevator=noop/' /etc/grub.conf

awk '$1 == "kernel" { $0 = $0 " elevator=noop" } { print } ' /etc/grub.conf