dodo - scriptable in place file editor
dodo is a work in progress so it is highly recommended you backup any files you are going to modify using dodo.
dodo is a non-interactive scriptable in place file editor.
dodo was born from the need to efficiently edit very large files (16GB plain sql dumps), I was unable to do so using my normal toolset (ed, sed or vim) and I realised that writing a tool specifically for this use case would be very simple.
cd dodo make make test
dodo is run and supplied with a single argument representing the filename to work on.
dodo then reads it's commands from stdin, note that dodo is non-interactive so will not start work until it's stdin input is finished (it sees eof).
in dodo all changes are flushed immediately; there are no concepts of 'saving', 'undo' or 'backups'.
dodo is really a very thin wrapper around
example dodo usage:
./dodo filename <<EOF p # print 100 bytes p5 # print 5 bytes ('hello') e/hello/ # expect string 'hello' b6 # goto byte 6 in file e/world/ # expect string 'world' w/marge/ # write string 'marge' (writes over 'world') b38 # goto byte 38 in file e/sl\/ash/ # expect string 'sl/ash' w/slashy/ # write over string 'sl/ash' with 'slashy' q # quit EOF
each of the commands is explained below in more detail.
dodo currently supports the following commands and syntax:
print specified number of bytes, if number is not specified will default to 100
place cursor at the start of 'number'-th line. Warning: this may be expensive in large files
check for 'string' at current cursor position, exit with error if not found.
expect does not move the cursor.
move cursor to absolute byte 'number' within file
write 'string' to current cursor position, this will overwrite any characters in the way
write moves the cursor by the number of bytes written
truncate the file at the current cursor position. Note that since the cursor can be inside or outside of the file, this can be used to truncate or extend files.
exit dodo, quit is not actually needed as EOF will trigger an implicit quit.
comments: dodo also supports comments
# this is a comment and spans until \n
in dodo whitespace is non-significant except in the case of a newline ('\n') terminating a comment
escape character: a backslash can be used as an escape character, useful mainly when the expected string or replacement string has to include a string delimiter (forward slash)