As the title suggests, is there a builtin library for moving a file and replacing an existing file if it exists?
I tried os.rename(path1, path2), but that doesn't seem to handle overwriting existing files.
Working with a pycom gpy, if that matters.
Thanks in advance
POSIX semantics require overwriting the target file in this case (and even atomically). So, "pycom gpy" seems to have a bug (or misfeature) in that regard. As a workaround, you can remove the target file with os.remove(path2) before rename.
Related
I want to know if there is a way to see the changes I made it to a linked files when I compare a project against a base line or a file to file.
I tried the compare utility from base line and file to file comparassion, and its works, if I add a linked file to x component or edit an existing one, it shows that there is change, but not in the best o most readeable way.
There is another way or tool to acomplished that?
Thank you.
pd_ sorry for my bad english
You can
Write your own comparison engine
Export the comparison xml and use that to present it in a way you like it better
Use LieberLiebers Lemontree
I just discovered some mentions of how nautilus used to read files named .hidden and hide files matching the patterns listed in them, and at some point that feature was moved to GIO g_file_info_get_is_hidden. However, I haven't been able to get it to work. If I put the exact name of a file into .hidden, it does get hidden, but I'd really like to be able to use a pattern. I can't find any solid or recent documentation about how this feature is supposed to work.
I'd particularly like to hide files matching hg-checkexec-*. Mercurial running under Emacs periodically creates bunches of these temporary files and they gum up my nautilus view.
Is this feature documented anywhere? How is it supposed to work?
Looking at the code, .hidden files as implemented in GIO support one filename per line, with no support for patterns. A .hidden file cannot list files in subdirectories — only those in the same directory.
I don’t know of any documentation about the feature. Please file a bug about adding it.
As a complement to Philip Withnall's answer, I've dived further into the source code, specifically the functions read_hidden_file() and file_is_hidden():
read_hidden_file() basically parses the .hidden in a directory and stores each line in as a key in a GLib HashTable object.
The object is created using g_hash_table_new_full() with parameters g_str_hash, g_str_equal, g_free, NULL. This mean keys are plain strings with comparison being a plain (case-sensitive) string equality, so no globs, regex or any patterns support.
It is populated using g_hash_table_add(), so not used as a key/value pair table but rather as a plain set, with keys being the elements themselves.
file_is_hidden() is called for each content (file or sub-directory) in a given directory. It uses g_hash_table_contains() to check if the file's basename is a key in above object, so no pattern search whatsoever.
So, as Phillip concluded, it seems there is indeed no support for any kind of globs, regexes or pattern seach in .hidden files. I would also die for a .gitignore-like syntax.
I need to replace a file on a zip using iOS. I tried many libraries with no results. The only one that kind of did the trick was zipzap (https://github.com/pixelglow/zipzap) but this one is no good for me, because what really do is re-zip the file again with the change and besides of this process be to slow for me, also do something that loads the whole file on memory and make my application crash.
PS: If this is not possible or way to complicated, I can settle for rename or delete an specific file.
You need to find a framework where you can modify how data is read and written. You would then use some form of mmap to essentially read and write small chunks. Searching on NSData and mmap resulted in this Post, however you can use mmap from the posix level too. Ps it will be slower than using pure memory no way around that.
Got it WORKING!! JXZip (https://github.com/JanX2/JXZip) has made exactly what I need, they link to libzip (http://www.nih.at/libzip/) that is a fully equiped library for working with ZIP files and JXZip have all the necessary Objective-C wrapper code. Thanks for all the replys.
For archive purposes, as the author of zipzap:
Actually zipzap does exactly what you want. If you replace an entry within a zip file, zipzap will do the minimum necessary to update it: it will skip writing all entries before the replaced entry, then write out the entry, then write out all entries after the replaced entry without recompressing. At the moment, it does require sufficient memory for the entries after the replaced entry though.
I have several files in a GridFS Document Store and what I'd like to do is to pipe this data into a zip file via stdin in NodeJS. So that I will end up with a zip file containing all these files.
Now my question is how can I give the files a valid filename inside of the zip file. I think I need to emulate/fake a file header containing the filename?
Any help is appreciated!
Thanks
I had problems when writing zip files with Node.js not long ago. I ended up doing something similar to what is described in Zip archives in node.js
I can't help you directly with your problem, but at least I hope I can point out some things:
Don't try to use node-archive. Even if the description says it allows to create zip files, the moment I read the source code (since documentation is unexistant) I realized that's just a lie. It only exposes methods for reading.
Using zip by spawning a process, like recommended on the provided link, seems to be the best way. Something that would work is copying the files to a local folder with whatever name you desire and then calling the zip command, just to delete the files afterwards.
The other option, which seems ok, is to use zipper (https://github.com/rubenv/zipper, although better just use npm). The reason I'm not really wishing to use it is because there's not that much flexibility, it seems to have been done in a day and it hasn't been modified since the first commit, so I'm not sure it will receive maintenance (sure, you could just fork it...).
I swear the day I have an entire free weekend with no work I will write a freaking module that does this as complete as possible. It's silly that there isn't and it shouldn't be that much struggle. blablablarant.
Edit:
Not sure if it was there before, but now I've been using the node-compress module (also using gzippo). It works fine.
I have a very common situation. I have a file, and I need to entirely overwrite that file with new contents. However, the original file is accessed on every page load (this is a web app), so it can't be missing for very long. A few ms is OK (though not ideal), a second is not OK.
Right now I do this by writing a temp file to the same directory and then renaming that temp file to the name of the new file. I'm just using the normal File::Temp and "rename" to do this, in Perl. I was wondering--is there some other recommended/better way to do this? Preferably one that doesn't require a CPAN module, as this is the only place in my system that I need to do this, and I don't want a whole new dependency just for this.
Oh, and all of this has to work on Windows, Linux, BSD, OS X, Solaris, and most other common platforms.
Here is the code in question, for those interested.
Your method seems just fine. It's quick, it's atomic, it uses core modules only, and File::Temp is a safe way to deal with temporary files. What more do you need?
I'd do it the same way you're doing it. At least on Unix-type OSes, a file rename is guaranteed to be atomic so you won't have any instants where either the original or the new files isn't there.
Rename is sufficient. However:
Is your temporary file at risk for race conditions? The filename should be randomized so nobody can cause problems by inserting their own file. Use an interface to mkstemp() if possible.