bfs - big file scanner
/usr/bin/bfs [-] filename
The bfs command is (almost) like ed(1) except that it is
read-only and processes much larger files. Files can be up
to 1024K bytes and 32K lines, with up to 512 characters,
including new-line, per line (255 for 16-bit machines). bfs
is usually more efficient than ed(1) for scanning a file,
since the file is not copied to a buffer. It is most useful
for identifying sections of a large file where csplit(1) can
be used to divide it into more manageable pieces for edit-
Normally, the size of the file being scanned is printed, as
is the size of any file written with the w (write) command.
The optional - suppresses printing of sizes. Input is
prompted with * if P and a carriage return are typed, as in
ed(1). Prompting can be turned off again by inputting
another P and carriage return. Note that messages are given
in response to errors if prompting is turned on.
All address expressions described under ed(1) are supported.
In addition, regular expressions may be surrounded with two
symbols besides / and ?:
> indicates downward search without wrap-around, and
< indicates upward search without wrap-around.
There is a slight difference in mark names; that is, only
the letters a through z may be used, and all 26 marks are
The e, g, v, k, p, q, w, =, !, and null commands operate as
described under ed(1). Commands such as ---, +++-, +++=,
-12, and +4p are accepted. Note that 1,10p and 1,10 will
both print the first ten lines. The f command only prints
the name of the file being scanned; there is no remembered
file name. The w command is independent of output diver-
sion, truncation, or crunching (see the xo, xt, and xc com-
mands, below). The following additional commands are avail-
Further commands are taken from the named file. When
an end-of-file is reached, an interrupt signal is
received or an error occurs, reading resumes with the
file containing the xf. The xf commands may be nested
to a depth of 10.
xn List the marks currently in use (marks are set by the
Further output from the p and null commands is
diverted to the named file, which, if necessary, is
created mode 666 (readable and writable by everyone),
unless your umask setting (see umask(1)) dictates oth-
erwise. If file is missing, output is diverted to the
standard output. Note that each diversion causes trun-
cation or creation of the file.
This positions a label in a command file. The label is
terminated by new-line, and blanks between the :
(colon) and the start of the label are ignored. This
command may also be used to insert comments into a
command file, since labels need not be referenced.
( . , . )xb/regular expression/label
A jump (either upward or downward) is made to label if
the command succeeds. It fails under any of the fol-
1. Either address is not between 1 and $.
2. The second address is less than the first.
3. The regular expression does not match at least one
line in the specified range, including the first
and last lines.
On success, . (dot) is set to the line matched and a jump is
made to label. This command is the only one that does not
issue an error message on bad addresses, so it may be used
to test whether addresses are bad before other commands are
executed. Note that the command, xb/^/ label, is an uncondi-
The xb command is allowed only if it is read from
someplace other than a terminal. If it is read from a
pipe, only a downward jump is possible.
Output from the p and null commands is truncated to,
at most, number characters. The initial number is 255.
The variable name is the specified digit following the
xv. The commands xv5100 or xv5 100 both assign the
value 100 to the variable 5. The command xv61,100p
assigns the value 1,100p to the variable 6. To refer-
ence a variable, put a % in front of the variable
name. For example, using the above assignments for
variables 5 and 6:
will all print the first 100 lines.
would globally search for the characters 100 and print each
line containing a match. To escape the special meaning of %,
a \ must precede it.
could be used to match and list %c, %d, or %s formats (for
example, "printf"-like statements) of characters, decimal
integers, or strings. Another feature of the xv command is
that the first line of output from a UNIX system command can
be stored into a variable. The only requirement is that the
first character of value be an !. For example:
xv6!expr %6 + 1
would put the current line into variable 35, print it, and
increment the variable 36 by one. To escape the special
meaning of ! as the first character of value, precede it
with a \.
stores the value !date into variable 7.
These two commands will test the last saved return
code from the execution of a UNIX system command
(!command) or nonzero value, respectively, to the
specified label. The two examples below both search
for the next five lines containing the string size:
xv5!expr %5 - 1
!if 0%5 != 0 exit 2
xv4!expr %4 - 1
!if 0%4 = 0 exit 2
If switch is 1, output from the p and null commands is
crunched; if switch is 0, it is not. Without an argu-
ment, xc reverses switch. Initially, switch is set for
no crunching. Crunched output has strings of tabs and
blanks reduced to one blank and blank lines
The following operand is supported:
Any file up to 1024K bytes and 32K lines, with up to
512 characters, including new-line, per line (255 for
16-bit machines). filename can be a section of a
larger file which has been divided into more manage-
able sections for editing by the use of csplit(1).
The following exit values are returned:
0 Successful completion without any file or command
>0 An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWesu |
csplit(1), ed(1), umask(1), attributes(5)
Message is ? for errors in commands, if prompting is turned
off. Self-explanatory error messages are displayed when
prompting is on.
Man(1) output converted with