bfs(1) bfs(1)NAME bfs - big file scanner SYNOPSIS bfs [-] filename DESCRIPTION bfs is a read-only editor that can process much larger files than standard editors. Files may be up to 1024K bytes (the maximum possible size) and 32K lines, with up to 512 charac- ters, including newline, 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) may be used to divide it into more manageable pieces for editing. Normally, the size of the file being scanned is printed, as is the size of any file written with the w command. The op- tional - suppresses printing of sizes. Input is prompted with * if P RETURN are typed as in ed. Prompting can be turned off again by entering another P 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: only the letters a through z may be used, and all 26 marks are remembered. The e, g, v, k, P, 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 filename. The w command is independent of output diversion, truncation, or crunching (see the xo, xt and xc commands, below). The following additional commands are available: xf file Further commands are taken from the named file. When an end-of-file is reached, an interrupt signal is re- ceived 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 k command). April, 1990 1
bfs(1) bfs(1)xo [file] Further output from the p and null commands is divert- ed to the named file, which, if necessary, is created mode 666. 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 newline, and blanks between the : 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- lowing 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, . 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 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 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. xv5100 or xv5 100 both assign the value 100 to the variable 5. 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: 2 April, 1990
bfs(1) bfs(1)1,%5p 1,%5 %6 will all print the first 100 lines. g/%5/p would search globally 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 lines containing printf of characters, decimal integers, or strings. Another feature of the xv command is that the first line of output from a A/UX system command can be stored into a variable. The only requirement is that the first character of value be an !. For ex- ample: .w junk xv5!cat junk !rm junk !echo "%5" xv6!expr %6 + 1 would put the current line into variable 5, print it, and increment the variable 6 by one. To escape the special meaning of ! as the first character of value, precede it with a \. xv7date 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 A/UX 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: xv55 : l /size/ xv5!expr %5 - 1 !if 0%5 != 0 exit 2 xbn l April, 1990 3
bfs(1) bfs(1)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 crunching. Crunched output has strings of tabs and blanks reduced to one blank and blank lines suppressed. EXAMPLES bfs text will invoke bfs with the file named text. FILES /bin/bfs SEE ALSO csplit(1), ed(1), regcmp(3X). DIAGNOSTICS ? for errors in commands, if prompting is turned off. Self-explanatory error messages when prompting is on. 4 April, 1990