cat(1) - NetBSD Manual Pages

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CAT(1)                  NetBSD General Commands Manual                  CAT(1)


NAME

     cat -- concatenate and print files


SYNOPSIS

     cat [-beflnstuv] [-B bsize] [-] [file ...]


DESCRIPTION

     The cat utility reads files sequentially, writing them to the standard
     output.  The file operands are processed in command line order.  A single
     dash represents the standard input, and may appear multiple times in the
     file list.  If no file operands are given, standard input is read.

     The word ``concatenate'' is just a verbose synonym for ``catenate''.

     The options are as follows:

     -B bsize
             Read with a buffer size of bsize bytes, instead of the default
             buffer size which is the blocksize of the output file.

     -b      Implies the -n option, but doesn't number blank lines.

     -e      Implies the -v option, and displays a dollar sign (`$') at the
             end of each line as well.

     -f      Only attempt to display regular files.

     -l      Set an exclusive advisory lock on the standard output file
             descriptor.  This lock is set using fcntl(2) with the F_SETLKW
             command.  If the output file is already locked, cat will block
             until the lock is acquired.

     -n      Number the output lines, starting at 1.

     -s      Squeeze multiple adjacent empty lines, causing the output to be
             single spaced.

     -t      Implies the -v option, and displays tab characters as `^I' as
             well.

     -u      The -u option guarantees that the output is unbuffered.

     -v      Displays non-printing characters so they are visible.  Control
             characters print as `^X' for control-X; the delete character
             (octal 0177) prints as `^?'.  Non-ascii characters (with the high
             bit set) are printed as `M-' (for meta) followed by the character
             for the low 7 bits.


EXIT STATUS

     The cat utility exits 0 on success, and >0 if an error occurs.


EXAMPLES

     The command:

           cat file1

     will print the contents of file1 to the standard output.

     The command:

           cat file1 file2 > file3

     will sequentially print the contents of file1 and file2 to the file
     file3, truncating file3 if it already exists.  See the manual page for
     your shell (e.g., sh(1)) for more information on redirection.

     The command:

           cat file1 - file2 - file3

     will print the contents of file1, print data it receives from the stan-
     dard input until it receives an EOF (`^D') character, print the contents
     of file2, read and output contents of the standard input again, then
     finally output the contents of file3.  Note that if the standard input
     referred to a file, the second dash on the command-line would have no
     effect, since the entire contents of the file would have already been
     read and printed by cat when it encountered the first `-' operand.


SEE ALSO

     head(1), hexdump(1), lpr(1), more(1), pr(1), tac(1), tail(1), view(1),
     vis(1), fcntl(2)

     Rob Pike, "UNIX Style, or cat -v Considered Harmful", USENIX Summer
     Conference Proceedings, 1983.


STANDARDS

     The cat utility is expected to conform to the IEEE Std 1003.2-1992
     (``POSIX.2'') specification.

     The flags [-Bbeflnstv] are extensions to the specification.


HISTORY

     A cat utility appeared in Version 1 AT&T UNIX.  Dennis Ritchie designed
     and wrote the first man page.  It appears to have been cat(1).


BUGS

     Because of the shell language mechanism used to perform output redirect-
     ion, the command ``cat file1 file2 > file1'' will cause the original data
     in file1 to be destroyed!  This is performed by the shell before cat is
     run.

NetBSD 9.0                       June 15, 2014                      NetBSD 9.0