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Full Discussion: cat a file from end to beginning
Top Forums UNIX for Dummies Questions & Answers cat a file from end to beginning Post 1810 by PxT on Friday 30th of March 2001 07:10:19 PM
Old 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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LEARN ABOUT LINUX

tac

TAC(1)								   User Commands							    TAC(1)

NAME

       tac - concatenate and print files in reverse

SYNOPSIS

       tac [OPTION]... [FILE]...

DESCRIPTION

       Write each FILE to standard output, last line first.  With no FILE, or when FILE is -, read standard input.

       Mandatory arguments to long options are mandatory for short options too.

       -b, --before
	      attach the separator before instead of after

       -r, --regex
	      interpret the separator as a regular expression

       -s, --separator=STRING
	      use STRING as the separator instead of newline

       --help display this help and exit

       --version
	      output version information and exit

AUTHOR

       Written by Jay Lepreau and David MacKenzie.

REPORTING BUGS

       Report tac bugs to bug-coreutils@gnu.org
       GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
       General help using GNU software: <http://www.gnu.org/gethelp/>
       Report tac translation bugs to <http://translationproject.org/team/>

COPYRIGHT

       Copyright (C) 2010 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

       rev(1).

       The  full  documentation  for tac is maintained as a Texinfo manual.  If the info and tac programs are properly installed at your site, the
       command

	      info coreutils 'tac invocation'

       should give you access to the complete manual.

GNU coreutils 8.5						   February 2011							    TAC(1)
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