[Old Thread] Limitation of length of path to Calibre Library

[TDReader]

I have been using Calibre for a considerable time, and am delighted with it.

The path to my Calibre library is long, of necessity, related to security, access & back-up procedures.

Today, after no problems previously, I received a message on loading Calibre (Version: 0.8.9) on my laptop (Win XPP SP3 patched to date), that my Calibre library could not be opened as the path to it was too long.

Nothing seems to have changed, and Calibre still works well on my desktop, (Win7 64 bit - SP 1 patched to date) where the path to the library is identical.

I think this is really a request to the development team to increase the length of the permitted path to the library to the maximum likely to be used - maybe 240 characters ?

Many thanks

Nigel

[kovidgoyal]

The path length is limited to 75 characters. If it were made longer then the path to individual book files would become too long for windows. If you need to use a long path, then map a drive to the long path, and use that in calibre.

[PeterT]

For a local drive you might have to use SUBST at the command prompt; not sure you can map a drive to a local directory.

[Halo]

Originally Posted by kovidgoyal

The path length is limited to 75 characters. If it were made longer then the path to individual book files would become too long for windows.

Windows supports paths of up to 32,767 characters if you prefix the path with "\\?\". For example, "\\?\D:\very long path". See the following web pages for reference:

1. http://www.codinghorror.com/blog/200...-too-long.html
2. http://msdn.microsoft.com/en-us/library/Aa365247

I successfully used this method last year when I was writing scripts to clean up files on a file server at work.

It works fine in Python. I think calibre can fix this limitation:

import os
p = "\\\\?\\" + os.getcwdu()
for i in range(10):
    p = os.path.join(p, 'x' * 100)
    os.mkdir(p)
    os.stat(p)
print len(p)

[kovidgoyal]

windows supports it, windows explorer doesn't, which means the files become inaccessible via windows explorer.

[FizzyWater]

Originally Posted by kovidgoyal

If you need to use a long path, then map a drive to the long path, and use that in calibre.

Wow. I am always learning something new here, this is great! I can use this, since I already know my path is currently longer than the 75 minimum (but haven't upgraded past 8.6 yet).

[FizzyWater]

Originally Posted by kovidgoyal

If you need to use a long path, then map a drive to the long path, and use that in calibre.

okay, dumb question

I tried this and it worked. End of the day I shut down the computer and now when I turned it back on, that drive is no longer showing.

Do I have to map it to a drive every time I reboot?

[itimpi]

Which method did you use to map the drive? In both the windows level drive mapping and the SUBST command option there is an option to make it persistent.

[PeterT]

Originally Posted by FizzyWater

okay, dumb question

I tried this and it worked. End of the day I shut down the computer and now when I turned it back on, that drive is no longer showing.

Do I have to map it to a drive every time I reboot?

At least with a networked mapped drive you can configure those to be permanent.

From the command line (not sure where it is in the GUI's) you can type

NET USE /PERSISTENT:YES

This will ensure that all network mapped drives will survive reboots.

[Halo]

Originally Posted by FizzyWater

I tried this and it worked. End of the day I shut down the computer and now when I turned it back on, that drive is no longer showing.

Make sure that "Reconnect at logon" is checked in the window when you are mapping the drive. That will make it sticky. See below circled in red.

[theducks]

Note:
Net Use is only valid if there is a Network connection UP and running (Link established) at the time it is issued.

[PeterT]

Originally Posted by theducks

Note:
Net Use is only valid if there is a Network connection UP and running (Link established) at the time it is issued.

Nooo... the NET USE /PERS:YES changes the default so that all further NET USE commands stay persistent.

[CaptainCrash]

Originally Posted by FizzyWater

okay, dumb question

I tried this and it worked. End of the day I shut down the computer and now when I turned it back on, that drive is no longer showing.

Do I have to map it to a drive every time I reboot?

You can make a SUBST command persistent by creating the following registry key, which might be simpler under some circumstances than the NET USE command - copy the following into a text file, amending where appropriate, save as "something.reg" and double-click to merge to the Registry. The change will be applied next time you reboot.

REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Session Manager\DOS Devices]
"X:"="\\??\\D:\\My\Very\Long\And\Complicated\Path\ To\My Data"

Note the double backslashes after the drive letter where your path exists, the normal single backslash won't work.

BTW, the forum software keeps inserting a space in "Contro l" in spite of my best efforts, obviously it should be "Control" without a space.

[chaley]

Originally Posted by CaptainCrash

You can make a SUBST command persistent ...

The other thing you can do is create a .bat file containing the SUBST command, then put the bat file in the Startup folder on the start menu. It will get run every time you start windows.

[FizzyWater]

Thanks to everyone who answered...I'm thinking of going with chaley's suggestion (I think it was made a little higher up by another poster as well). I don't want to mess with the registry, but I already know my path is too long and I've been holding off upgrading Calibre because of it. I need a simple method that I'll remember to transfer to my notebook (which serves as a backup for me) as well.