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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 displays 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 addition, 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:

  /pattern/
	  Searches forward with wraparound for pattern.

  ?pattern?
	  Searches backward with wraparound for pattern.

  >pattern>
	  Searches forward without wraparound for pattern.

  <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:

  xf file
      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.

  xo [file]
      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.

  :label
      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.

  [address1[,address2]xb/pattern/label
      Sets the current line to the line containing pattern and jumps to label
      in the current command file if pattern 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.

  xt number
      Truncates output from the p and null subcommands to number characters.
      The default number is 255.

  xv[number]  [value]
      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

  xbz label
      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).

  xbn label
      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).

  xc [switch]
      Turns compressed output mode on or off.  (Compressed output mode
      suppresses 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)

Index for Section 1

Alphabetical listing for B

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