@node Invoking
@chapter Invoking

@command{scrotty} recognises the options:

@table @option
@item -h
@itemx --help
Print usage information and exit.
@item -v
@itemx --version
Print program name and version and exit.
@item -c
@itemx --copyright
Print copyright information and exit.
@item -d
@itemx --device NO
Select a framebuffer device, by index, to
screenshot.  All framebuffers are screenshoot
if this option is omitted.
@item -e
@itemx --exec CMD
Run a command for each saved image.
@end table

Each option can only be used once.

In addition to these options, a filename
pattern, that does not start with a dash,
can be added. This filename pattern selects
with what filename the image should be saved.
Alternatively, you can pipe stdout to another
program, or file, and the framebuffer will
be sent there. This requires that @option{--exec}
is unused.

Both the @option{--exec} and filename pattern
parameters can take format specifiers that are
expanded by @command{scrotty} when encountered.
There are two types of format specifier.
Characters preceded by a `%' are interpreted
by @code{strftime}. See @ref{strftime} or the
manual for your implemenation of @command{strftime}
for examples. These options may be used to refer
to the current date and time. The second kind are
internal to scrotty and are prefixed by `$' or
`\'. The following specifiers are recognised:

@table @asis
@item `@code{$i}'
Framebuffer index.
@item `@code{$f}'
Image filename/pathname.
Ignored in the filename pattern.
@item `@code{$n}'
Image filename.
Ignored in the filename pattern.
@item `@code{$p}'
Image width multiplied by image height.
@item `@code{$w}'
Image width.
@item `@code{$h}'
Image height.
@item `@code{$$}'
Expands to a literal `$'.
@item `@code{\n}'
Expands to new line.
@item `@code{\\}'
Expands to a literal `\'.
@item `@code{\ }'
Expands to a literal ` '.                                           
@end table

A space that is not prefixed by a backslash in
@option{--exec} is interpreted as an argument
delimiter. This is the case even at the beginning
and end of the string and if a space was the
previous character in the string.

For example,
@command{scrotty `%Y-%m-%d_$wx$h.$i.png` --exec 'cp $f ~/.backups/shots/'}
create a file called something like @file{2014-10-28_1792x1344.0.png}
for your first framebuffer and @file{2014-10-28_1792x1344.1.png} for
your second framebuffer, and copies the saved images to @file{~/.backups/shots/}.