Block commands¶

D [n]

Delete the n'th block. Without n, all found blocks are deleted from the output stream.

I string

Insert the string string before the block.

A string

Append the string string at the end of block.

J n

Skip n blocks before executing commands after this command.

L n

Leave all blocks unmodified starting from block number n. Affects only commands after this command.

N

Before printing a block, the file name in which the block starts is printed.

F f

Before printing a block, the input stream offset at the begining of the block is printed. f can be H, D or O for Hexadecimal, Decimal or Octal format of offset.

B f

Before printing a block, the block number is printed (first block == 1) f can be H, D or O for Hexadecimal, Decimal or Octal format of block number.

> file

Before printing a block, the contents of file file is printed.

< file

After printing a block, the contents of file file is printed.

Byte commands¶

n in byte commands is offset from the beginning of current block (starts from zero).

r n string

Replace bytes starting at position n with string string.

i n string

Insert string starting at position n.

p format

The contents of block is printed in format defined by format. format can have any of the formats H, D, O, A and B for Hexadecimal, Decimal, Octal, Asciii and Binary.

s/search/replace/

Replace all occurrences of search with replace.

y/source/dest/

Translate bytes in source to the corresponding bytes in dest. Source and dest must have equal length.

d n m|*

Delete m bytes starting from the offset n. If * is defined instead of m, then all bytes starting from n are deleted.

c from to

Convert bytes from format from to to. Currently supported formats are:

BCD Binary coded decimal

ASC Ascii

j n

Commands after the j-command are ignored for first n bytes of the block.

l n

Commands after the l-command are ignored from n'th byte of the block.

w file

Write bytes from the current block to file file. Commands before w-command have effect to what will be written. %B or %nB in file will be replaced by current block number. n in %nB is field length, leading zero in n causes the block number to be left padded with zeroes.

& c

Performs binary and with c.

| c

Performs binary or with c.

^ c

Performs binary xor with c.

~

Performs binary negation.

u n c

All bytes from start of the block to offset n are replaced by c.

f n c

All bytes starting from offset n to end of the block are replaced by c.

x

Exchange the contents of nibbles (half an octet) of bytes.

Nonvisible characters in strings can be escaped same way as in block definition strings. Character '/' in s and y commands can be any visible character.

Note that the D, A, I, F, B, c, s, i, y, p, <, > and d commands cause the length of input and output streams to be different.