How to Append a Text/Line to root Owned Files with Sudo Access
Today, I came across a situation where I was writing a script for automation. In the script, I had to append a line to file /etc/fstab which is owned by root. I was using the below line in the script, but it was failing.
$ sudo echo "/dev/vg01/lvol0 /mnt/data xfs defaults 0 0" >> /etc/fstab -bash: /etc/fstab: Permission denied
Below are the ways to achieve this:
1. Using tee command:
$ echo "/dev/vg01/lvol0 /mnt/data xfs defaults 0 0" | sudo tee -a /etc/fstab /dev/vg01/lvol0 /mnt/data xfs defaults 0 0
$ tail -n 1 /etc/fstab /dev/vg01/lvol0 /mnt/data xfs defaults 0 0
Here, tee: read from standard input and write to standard output and files. -a: append to the given FILEs, do not overwrite.
2. Using bash/sh command:
$ sudo bash -c "echo '/dev/vg01/lvol0 /mnt/data xfs defaults 0 0' >> /etc/fstab"
-c: If the -c option is present, then commands are read from string.