working with large files directly opening the file in an editor will probably be inefficient (due to high memory utilization) because most text editors usually try to read the whole file into memory first. instead, one can use less to view the contents of such a large file, scrolling up and down page by page, without the system having to place the entire file in memory before starting. less somefile cat somefile | less head reads the first few lines...

cat cat read / write / concatenate tac prints the lines of a file in reverse order. each line remains the same, but the order of lines is inverted. cat > file cat » file (any subsequenet lines are appended to the file, until CTRL-D is typed) using cat interactively echo -e option, along with the following switches, is used to enable special character sequences, such as the newline character or horizontal tab

elevating to root account sudo configuration files are stored in the /tec/sudoers file and in the /etc/sudoers.d directory. by default, the sudoers.d directory is empty

filesystems lick /proc are called pseudo filesystems because they exist only in memory /var may be put in its own filesystem so that growth can be contained and not fatally affect the ststem /boot contains the basic files needed to boot the system

1. Backing Up Data cp <-> rsync rsync is more efficient, because it checks if the file being copied already exists. rsync copies only the parts of files that have actually changed, it can be very fast cp can only copy files to and from destinations on the local machine (unless mounted using NFS), rsync can also be used to copy files from one machine to another. someone@host:path 2. Using rsync a very useful way to back up a project directory might be to use the following command....