BFS(1) DOMAIN/IX SYS5 BFS(1)
NAME
bfs - big file scanner
USAGE
bfs [-] name
DESCRIPTION
Bfs is similar to ed(1), except that it is read-only and
processes much larger files. Maximum file size is 1024K
bytes. Files can be up to 32K lines in length, with as many
as 512 characters per line, including newline (255 charac-
ters 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 editing.
Unless you specify a dash (-) option, bfs prints the size of
the file being scanned. If P and a carriage return are
typed, it prompts input with an asterisk (*). 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.
EXPRESSIONS
Bfs supports all address expressions described under ed(1).
Thus, regular expressions may be surrounded with a slash (/)
and question mark (?). In addition, a greater-than charac-
ter (>) indicates a downward search without wrap-around, and
a less-than character (<) indicates an upward search without
wrap-around. There is a slight difference in mark names:
only the letters a through z may be used, and all 26 marks
are remembered.
COMMANDS
The e, g, k, p, q, v, 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
filename. The w command is independent of output diversion,
truncation, or crunching (see the xo, xt, and xc commands
below). The following commands are also available:
xf file
Take further commands 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 ten.
Printed 12/4/86 BFS-1
BFS(1) DOMAIN/IX SYS5 BFS(1)
xn
List the marks currently in use (marks are set by the k
command).
xo [file]
Divert further output from the p and null commands to the
named file, which, if necessary, is created in mode 666.
If file is missing, divert output to the standard output.
Each diversion truncates or creates a file.
: label
Position a label in a command file. Ignore blanks between
the colon (:) and the start of the label. Terminate label
with newline. May also be used to insert comments into a
command file, since labels need not be referenced.
( . , . )xb/regular expression/label
Make a jump (either upward or downward) to label if suc-
cessful. Will fail under any of the following conditions:
1. Neither address is 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.
If successful, set the current line, indicated by a period
(.), to the line matched. Then, jump to label. This com-
mand 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 xb/^/ label is an unconditional jump.
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.
xt number
Truncate output from the p and null commands to a maximum
of number characters (initially 255).
xv[digit][spaces][value]
Specify digit as the variable name following xv. The com-
mands 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 percent
sign (%) in front of the variable name. For example, using
the above assignments for variables 5 and 6:
1,%5p
BFS-2 Printed 12/4/86
BFS(1) DOMAIN/IX SYS5 BFS(1)
1,%5
%6
all print the first 100 lines.
To globally search for the characters 100 and print each
line containing a match, type:
g/%5/p
To escape the special meaning of a percent sign (%), a
backslash (\) must precede it.
The following can be used to match and list lines contain-
ing printf of characters, decimal integers, or strings:
g/".*\%[cds]/p
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 exclamation point (!). For example:
.w junk
xv5!cat junk
!rm junk
!echo ``%5''
xv6!expr %6 + 1
puts the current line into variable 5, prints it, and
increments the variable 6 by one. To escape the special
meaning of an exclamation point (!) as the first character
of value, precede it with a slash (\).
xv7\!date
stores the value !date into variable 7.
xbz label
xbn label
Test the last saved return code from the execution of a
UNIX system command (!command) or non-zero value, respec-
tively, to the specified label. For example, to search for
the next five lines containing the string called ``size'',
you might do the following:
xv55
: l
/size/
xv5!expr %5 - 1
Printed 12/4/86 BFS-3
BFS(1) DOMAIN/IX SYS5 BFS(1)
!if 0%5 != 0 exit 2
xbn l
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 argument,
xc reverses switch. Initially switch is set for no crunch-
ing. Crunched output has strings of tabs and blanks
reduced to one blank and blank lines suppressed.
DIAGNOSTICS
? for errors in commands, if prompting is turned off.
Self-explanatory error messages when prompting is on.
RELATED INFORMATION
csplit(1), ed(1), regcmp(3X).
BFS-4 Printed 12/4/86