bfs(1)							      General Commands Manual							    bfs(1)

NAME

       bfs - Scans files

SYNOPSIS

       bfs [-] file...

       The bfs command is a read-only line editor typically used to scan files.

OPTIONS

       Suppresses the display of file sizes.  Normally, bfs displays the size in bytes of the file being scanned.

DESCRIPTION

       The bfs command is similar to the ed command, but has some additional subcommands and the ability to process much larger files.

       Input files can be up to 32K lines long, with up to 512 characters per line. The command bfs is usually more efficient than ed for scanning
       a file because the file is not copied to a buffer.  It is useful for identifying appropriate lines at which to use the csplit command  when
       dividing a large file into more manageable pieces for editing.

       If  you	enter the P subcommand, bfs prompts you with * (asterisk).  You can turn off prompting by entering a P again. The command bfs dis-
       plays error messages only when prompting is turned on.

   Pattern Searches
       The bfs command supports all the address expressions described in ed(1). Regular expressions are covered in detail in  grep(1).	 In  addi-
       tion, you can instruct bfs to search forward or backward through the file with or without wraparound.  If you specify a forward search with
       wraparound, bfs continues searching from the beginning of the file after it reaches the end of the file.  If you specify a backward  search
       with  wraparound,  it  continues  searching  backward from the end of the file after it reaches the beginning.  A search without wraparound
       stops at the beginning or end of the file.

       Specify the four types of searches as follows: Searches forward with wraparound for pattern.  Searches backward with  wraparound  for  pat-
       tern.  Searches forward without wraparound for pattern.	Searches backward without wraparound for pattern.

       The pattern matching routine of bfs differs somewhat from the one used by ed and includes additional features.

       Only lowercase letters a through z can be used, and all 26 marks are remembered.  See ed(1) for information on mark names.

SUBCOMMANDS

       The e, g, v, k, n, p, q, w, = , !, and null subcommands operate the same as for ed.

       Subcommands such as --, +++-, +++=, -12, and +4p are accepted.  Note that 1,10p and 1,10 both display the first 10 lines.

       The  f  subcommand displays only the name of the file being scanned; there are no remembered filenames.	The w subcommand is independent of
       output diversion, truncation, or compression.  See the xo, xt, and xc subcommands that follow.

       The following additional subcommands are available: Reads bfs subcommands from file.  When bfs reaches the end of file or receives  an  INT
       signal or if an error occurs, bfs resumes scanning the file that contains the xf subcommand. The xf subcommands can be nested to a depth of
       10.  Sends further output from the p and null subcommands to the named file, which is created with read and write permission granted to all
       users.	If  you  do  not  specify  a file, bfs writes to standard output. Note that each redirection to a file creates the specified file,
       deleting an existing file if necessary.	Positions a label in a subcommand file.  The label is ended  with  a  newline  character.   Spaces
       between the : (colon) and the start of the label are ignored.  This subcommand can be used to insert comments into a subcommand file, since
       labels need not be referenced.  Sets the current line to the line containing pattern and jumps to label in the current command file if pat-
       tern  is matched within the designated range of lines. The jump fails under any of the following conditions: Either address1 or address2 is
       not between the first and last lines of the file.  address2 is less than address1.  The pattern does not match at least	one  line  in  the
       specified range, including the first and last lines.

	      This  subcommand	is  the only one that does not issue an error message on bad addresses, so it can be used before other subcommands
	      are run to test whether addresses are bad.  Note that the following subcommand is an unconditional jump: xb/^/label

	      The xb subcommand is allowed only if it is read from a file or a pipe.  If it is read from a pipe, only a downward jump is possible.
	      Truncates  output  from the p and null subcommands to number characters.	The default number is 255.  Assigns the specified value to
	      the variable named number (0 to 9).  You can put one or more spaces between number and value.  For example: xv5 100 xv6 1,100p

	      assigns the value 100 to the variable 5 and the value 1,100p to the variable 6.

	      To reference a variable, put a % (percent sign) in front of the variable name.  Given the preceding assignments for variables 5  and
	      6, the following three subcommands each display the first 100 lines of a file: 1,%5p 1,%5 %6

	      To escape the special meaning of %, precede it with a  (backslash).  g/".*\%[cds]/p

	      matches and lists lines containing printf variables (%c, %d, or %s).

	      You  can	also  use  the	xv subcommand to assign the first line of command output as the value of a variable.  To do this, make the
	      first character of value an !  (exclamation point), followed by the command name.  For example, the following  command  line  stores
	      the first line of the file junk in the variable 5: xv5 !cat junk

	      To  escape  the  special meaning of !  as the first character of value, precede it with a  (backslash).	For example, the following
	      command line stores the value !date in the variable 7: xv7 !date Tests the last saved exit value from a shell command and jumps	to
	      label in the current command file if the value is 0 (zero).  Tests the last saved exit value from a shell command and jumps to label
	      in the current command file if the value is not 0 (zero).  Turns compressed output mode on or off.   (Compressed	output	mode  sup-
	      presses empty lines and replaces multiple spaces and tabs with a single space.)

	      If  switch  is 1, output from the p and null subcommands is compressed; if switch is 0 it is not.  If you do not specify switch, the
	      current value of switch reverses.  Initially, switch is set to 0.

SEE ALSO

       Commands:  csplit(1), ed(1), grep(1)

       Functions:  regexp(3)

																	    bfs(1)