Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
BASE64(1)		    General Commands Manual		     BASE64(1)

       base64 -	encode / decode	binary file as RFC 1341	MIME base64

       base64 -d|-e [ -n ] [ -u	] [ infile [ outfile ] ]

       The  MIME  (Multipurpose	 Internet  Mail	Extensions) specification (RFC
       1341 and	successors) defines a mechanism	for encoding arbitrary	binary
       information  for	 transmission  by  electronic mail.  Triplets of 8-bit
       octets are encoded as groups of four characters,	 each  representing  6
       bits of the source 24 bits.  Only characters present in all variants of
       ASCII and EBCDIC	are used, avoiding incompatibilities in	other forms of
       encoding	such as	uuencode/uudecode.

       base64  is  a  command  line utility which encodes and decodes files in
       this format.  It	can be used within a pipeline as an encoding or	decod-
       ing  filter, and	is most	commonly used in this manner as	part of	an au-
       tomated mail processing system.

       --copyright Print program copyright information.

       -d, --decode
		   Decodes the input, previously created by base64, to recover
		   the original	input file.

       -e, --encode
		   Encodes  the	 input into an output text file	containing its
		   base64 encoding.

       -n, --noerrcheck
		   Suppress error checking when	decoding.   By	default,  upon
		   encountering	a non white space character which does not be-
		   long	to the base64 set, or discovering the  input  file  is
		   incorrectly padded to a multiple of four characters,	base64
		   issues an error message and terminates processing with exit
		   status  1.	The -n option suppresses even this rudimentary
		   error checking; invalid characters are silently ignored and
		   the	output truncated to the	last three valid octets	if the
		   input is incorrectly	padded.

       -u, --help  Print how-to-call information.

       --version   Print program version information.

       base64 returns status 0 if processing was completed without  errors,  1
       if  an  I/O  error  occurred or errors were detected in decoding	a file
       which indicate it is incorrect or incomplete, and 2 if processing could
       not be performed	at all due, for	example, to a nonexistent input	file.

       If  no  infile  is  specified or	infile is a single ``-'', base64 reads
       from standard input; if no outfile is given, or	outfile	 is  a	single
       ``-'',  output  is  sent	 to standard output.  The input	and output are
       processed strictly serially; consequently base64	may be used  in	 pipe-

       Little  or no error checking is done when decoding, other than validat-
       ing that	the input consists of a	multiple of four characters in the en-
       coding  set.   This  is inherent	in the design of base64, which assumes
       transmission integrity is the responsibility of a  higher-level	proto-

       Please report bugs and documentation errors to

       uudecode(1), uuencode(1), RFC1341

	    John Walker

       This  software  is in the public	domain.	 Permission to use, copy, mod-
       ify, and	distribute this	software and its documentation for any purpose
       and  without  fee is hereby granted, without any	conditions or restric-
       tions.  This software is	provided ``as is'' without express or  implied

       This is version 1.4 of base64.  The current version of this program may
       be downloaded from

4th Berkeley Distribution	  20 FEB 2001			     BASE64(1)


Want to link to this manual page? Use this URL:

home | help