# 1.8 Command format

The format of the commands looks something like that:

    [#][!][cmd] [arg] [@ offset:size|@@ flags|@@=off:sz ..] [> file] [| shell-pipe] [~grep#[]] [ && ...]

'N' must be a numeric value. Commands are named with single chars [a-zA-Z]. So, if we prefix the command with a number. The following command will be executed as many times as we specify.

    px    # run px
    3px   # run 3 times 'px'

The '!' prefix is used to scape to the shell. If a single exclamation is used then commands will be send to the system() hook defined in the loaded IO plugin. This is used, for example in the ptrace IO plugin which accepts debugger commands from this interface. To run commands to the shell we should type two '!!' exclamations before the command.

Some examples:

    !step                 ; call debugger 'step' command
    px 200 @ esp          ; show 200 hex bytes at esp
    pc > file.c           ; dump buffer as a C byte array to file
    wx 90 @@ sym.*        ; write a nop on every symbol
    pd 2000 | grep eax    ; grep opcodes using 'eax' register
    x 20 && s +3 && x 40  ; multiple commands in a single line

The '@' character is used to specify a temporary offset where the command at the left will be executed. By using a ':' we can specify a temporaly block size too.

The '~' character enables the internal grep which can be used to filter the output of any command. The usage is quite simple:

    pd 20~call            ; disassemble 20 instructions and grep for 'call'

We can either grep for columns or rows:

    pd 20~call#0          ; get first row
    pd 20~call#1          ; get second row

Or even combine them:

    pd 20~call[0]#0       ; grep first column of the first row matching 'call'

The use of internal grep is a key feature for scripting radare, because is used to iterate over list of offsets or data processed from disassembly, ranges, or any other command. Here's an example of usage. See macros section (iterators) for more information.

TODO : add example