User Commands bfs(1)
NAME
bfs - big file scanner
SYNOPSIS
/usr/bin/bfs [-] filename
DESCRIPTION
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-
ing.
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
remembered.
bfs Commands
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
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User Commands bfs(1)
available:
xf file
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 con-
taining 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 k
command).
xo [file]
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 otherwise. If file
is missing, output is diverted to the standard output.
Note that each diversion causes truncation or creation
of the file.
: label
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 follow-
ing conditions:
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
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User Commands bfs(1)
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 unconditional jump.
The xb command is allowed only if it is read from some-
place other than a terminal. If it is read from a pipe,
only a downward jump is possible.
xt number
Output from the p and null commands is truncated to, at
most, number characters. The initial number is 255.
xv[digit][spaces][value]
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 reference a variable,
put a % in front of the variable name. For example,
using the above assignments for variables 5 and 6:
1,%5p
1,%5
%6
will all print the first 100 lines.
g/%5/p
would globally search for the characters 100 and print
each line containing a match. To escape the special
meaning of %, a \ must precede it.
g/".*\%[cds]/p
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:
.w junk
xv5!cat junk
!rm junk
!echo "%5"
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User Commands bfs(1)
xv6!expr %6 ] 1
would put the current line into variable 35, print it,
and increment the variable 36 by one. To escape the spe-
cial meaning of ! as the first character of value, pre-
cede it with a \.
xv7\!date
stores the value !date into variable 7.
xbz label
xbn label
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:
Example 1:
xv55
: l
/size/
xv5!expr %5 - 1
!if 0%5 != 0 exit 2
xbn l
Example 2:
xv45
: l
/size/
xv4!expr %4 - 1
!if 0%4 = 0 exit 2
xbz l
xc [switch]
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 suppressed.
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User Commands bfs(1)
OPERANDS
The following operand is supported:
filename 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 manageable sections for edit-
ing by the use of csplit(1).
EXIT STATUS
The following exit values are returned:
0 Successful completion without any file or command
errors.
>0 An error occurred.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWesu
SEE ALSO
csplit(1), ed(1), umask(1), attributes(5)
DIAGNOSTICS
Message is ? for errors in commands, if prompting is turned
off. Self-explanatory error messages are displayed when
prompting is on.
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