What does tail command do?
The tail command shows you data from the end of a file. Usually, new data is added to the end of a file, so the tail command is a quick and easy way to see the most recent additions to a file. It can also monitor a file and display each new text entry to that file as they occur.
How do you get a cat line number?
There are two command line options available in the cat command that allows you to display line numbers, –number (-n) and –number-nonblank (-b), according to your requirement. The option -n or –number will print out the line numbers of all lines, including the blank or empty lines in the file.
Why do airplane tail numbers start with N?
Where do N-numbers come from? The U.S. received the “N” as its nationality designator under the International Air Navigation Convention, held in 1919. The Convention prescribed an aircraft-marking scheme of a single letter indicating nationality followed by a hyphen and four identity letters (for example, G-REMS).
How can I tell tail to use offsets instead of lines?
You can tell tail to use offsets in bytes instead of lines by using the -c (bytes) option. This could be useful if you have a file of text that was formatted into regular-sized records. Note that a newline character counts as one byte.
How does tail display lines from the start of a file?
Displaying Lines from the Start of a FIle The + (count from the start) modifier makes tail display lines from the start of a file, beginning at a specific line number. If your file is very long and you pick a line close to the start of the file, you’re going to get a lot of output sent to the terminal window.
Is the + n argument of tail always the same?
This is measurably faster on large files. Beware that the +N argument of tail is not the number of lines to skip, but one plus that — it’s the number of the first line to print with lines numbered from 1. Either way, the output file is only opened once, but the input file is traversed once for each snippet to extract.
How to use head and tail to print specific lines?
How could I use head and tail to do this? where firstline = $2 and lastline = $3 and filename = $1. Aside from the answers given by fedorqui and Kent, you can also use a single sed command: #!/bin/sh filename=$1 firstline=$2 lastline=$3 # Basics of sed: # 1. sed commands have a matching part and a command part.