Re: [wmii] adding data to 9p files using wmiir
On Wed, Mar 18, 2009 at 07:30:01PM -0400, Kris Maglione wrote: > On Thu, Mar 19, 2009 at 12:16:10AM +0100, Martin Kraus wrote: >> Basicaly I'd expect this not to work, since wmiir is reading and at the same >> time overwriting the data. It had worked as far as I've tried. Is it because >> wmiir first reads all the data and then outputs it so that the other wmiir >> write will just overwrite alread read data, or have I been lucky and reading >> from the file was just always quicker then writing to it? >> >> Simply put, can I safely use the above syntax or should I read it into a >> variable and then overwrite it? > > Well, you can safely use it as long as you have less than about 8K of > colrules. It actually works because wmii truncates those files to the > last byte written on every write, but wmiir doesn't write anything to the > filesystem until it recieves something from stdin. Since it won't recieve > anything until the first wmiir finishes its read, you're fine as long as > the first read returns the whole file (which it will if it's under 8K). > > So, that was more than you asked for. How about this: I'll just add a -a > flag to 'wmiir write'. Thanks. I thought as much. I realised I can actually have a look at the source since it is open:) Even with my rusty C knowledge it is quite obvious once I've started using a bit of that thing of mine called brain. Sometimes I think I'm getting too old. thanks for the complete explanation. mk
Re: [wmii] adding data to 9p files using wmiir
On Thu, Mar 19, 2009 at 12:16:10AM +0100, Martin Kraus wrote: Basicaly I'd expect this not to work, since wmiir is reading and at the same time overwriting the data. It had worked as far as I've tried. Is it because wmiir first reads all the data and then outputs it so that the other wmiir write will just overwrite alread read data, or have I been lucky and reading from the file was just always quicker then writing to it? Simply put, can I safely use the above syntax or should I read it into a variable and then overwrite it? Well, you can safely use it as long as you have less than about 8K of colrules. It actually works because wmii truncates those files to the last byte written on every write, but wmiir doesn't write anything to the filesystem until it recieves something from stdin. Since it won't recieve anything until the first wmiir finishes its read, you're fine as long as the first read returns the whole file (which it will if it's under 8K). So, that was more than you asked for. How about this: I'll just add a -a flag to 'wmiir write'. -- Kris Maglione When a religion is good, I conceive it will support itself; and when it does not support itself, and God does not take care to support it so that its professors are obliged to call for help of the civil power, 'tis a sign, I apprehend, of its being a bad one. --Benjamin Franklin
