Member Avatar for picass0

i wanted to printout the last entry of the file without passing in any arguments but how can i able to do it? i know how to print out where argument is supplied and doing a grep to match it.

example inside the file i have:
apple:2:1:3
orange:1:2:3
grape:2:3:4

i wanted only to print out(last entry of my file):
grape:2:3:4

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  • Latest Post Latest Post by ghostdog74

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Short summary: wanted the last line of a file with no arguments. pointed out a sed-based approach and mentioned using tail; both are valid. Below are a few alternative methods, practical tips for edge cases, and performance/portability notes to help pick the right tool.

A simple, portable one-liner using awk (available on virtually all Unix-like systems):

awk 'END{print}' filename

To skip trailing blank lines and print the last non-empty line:

awk 'NF{last=$0} END{print last}' filename

If only POSIX shell builtins are available, a read-loop captures the last line reliably (handles lines without a trailing newline too):

last=
while IFS= read -r line; do
  last="$line"
done < filename
printf '%s\n' "$last"

On Linux, reversing the file and taking the first line is also convenient (note: tac is not always present on other Unixes):

tac filename | head -n 1

Performance and portability notes: for very large files, utilities that seek from the end (the usual implementation of tail) are fastest; line-at-a-time filters scan the whole file and can be slower. Also consider empty files (these methods produce no output), files with Windows CRLF (you may need to strip \r), and whether you want to ignore trailing blank lines. For more on behavior and performance characteristics of standard tools, see the POSIX tail spec (POSIX tail specification) and the GNU awk manual (gawk manual).

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Member Avatar for masijade 
sed -n '$p' filename
commented: I'll have to look into this - don't quite understand how it works. Nice! +1
Member Avatar for picass0

thanks masijade! thanks for ur help!!!

Member Avatar for omrsafetyo

^ Nice and simple, just the way I like it... though I'm more interested in the sed example.

Member Avatar for masijade

Or
tail -1 file

True. I like to give somewhat obscure answers to things that I belive are probably/possibly homework questions. That way, if they are not a homework question, the OP has something (s)he can use, and if they are, the teacher knows, as soon as (s)he sees it, that the student probably did not come up with it themselves. ;-)

Member Avatar for ghostdog74

sed will be slower than tail for huge files. Just a tip

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