03-30-2001
Quote:
cat file | perl -e 'print reverse <>'
Just do perl -e 'print reverse <>' file
However, the down side to the perl method is that the whole file must be read into memory. Could be a memory-hog for extremely large files. I believe 'tac' uses seek to read through the file, so that you can view files of arbitrary size. Usually not a problem though. The perl method is good if you dont have 'tac' installed.
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CAT(1) User Commands CAT(1)
NAME
cat - concatenate files and print on the standard output
SYNOPSIS
cat [OPTION]... [FILE]...
DESCRIPTION
Concatenate FILE(s) to standard output.
With no FILE, or when FILE is -, read standard input.
-A, --show-all
equivalent to -vET
-b, --number-nonblank
number nonempty output lines, overrides -n
-e equivalent to -vE
-E, --show-ends
display $ at end of each line
-n, --number
number all output lines
-s, --squeeze-blank
suppress repeated empty output lines
-t equivalent to -vT
-T, --show-tabs
display TAB characters as ^I
-u (ignored)
-v, --show-nonprinting
use ^ and M- notation, except for LFD and TAB
--help display this help and exit
--version
output version information and exit
EXAMPLES
cat f - g
Output f's contents, then standard input, then g's contents.
cat Copy standard input to standard output.
AUTHOR
Written by Torbjorn Granlund and Richard M. Stallman.
REPORTING BUGS
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report cat translation bugs to <http://translationproject.org/team/>
COPYRIGHT
Copyright (C) 2017 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
tac(1)
Full documentation at: <http://www.gnu.org/software/coreutils/cat>
or available locally via: info '(coreutils) cat invocation'
GNU coreutils 8.28 January 2018 CAT(1)