reading entries from multiple files

Question

I have few files like A.txt, B.txt and C.txt, each having a only single number in it i.e A.txt has 45 B.txt has 35 and C.txt has 100. How could I read these entries from each files and report with its corresponding file name.

output:

45 A.txt

35 B.txt

100 C.txt

thanks!

Answer 1

One way:

awk '{ print $0 " " FILENAME }' A.txt B.txt C.txt

Output:

45 A.txt
35 B.txt
100 C.txt

Answer 2

Another answer, which doesn't involve awk but gives you the output in another format:

$ grep '.*' *.txt
A.txt:45
B.txt:35
C.txt:100

Answer 3

With shell only:

for f in {A,B,C}.txt; do echo $(<$f) $f; done

Output:

45 A.txt
35 B.txt
100 C.txt