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After running Disk Usage Analyzer on the file system, I am looking for ways to remove unneeded files on my Live USB.

  1. Firstly, is there anything I can do about the files in the casper archive? For example, I noticed that there exists a directory /rofs, which I'm sure stands for read-only file system, the one stored in the read-only casper file, so I can't removing anything in it. Specifically, I removed LibreOffice yet /rofs/usr/lib/libreoffice takes up 222 MB of precious storage, as does Thunderbird and a bunch of other things.

  2. What can I clear regarding the apt program files. /var/lib/apt/lists takes up 115 MB, and /var/cache/apt (not the archives directory) is 139 MB. The /var/cache/apt folder is made up of several ~35 MB files, and I don't know if they are all necessary:

    ubuntu@ubuntu:/var/cache/apt$ du -ah
    4.0K    ./archives/partial
    0       ./archives/lock
    28K     ./archives
    4.0K    ./typescript
    34M     ./srcpkgcache.bin
    31M     ./srcpkgcache.bin.ifDvIA
    34M     ./pkgcache.bin.3IHVIK
    32K     ./pkgcache.bin.h2Zwz7
    36M     ./pkgcache.bin
    133M    .
  3. I already clear browsing data regularly when I use chrome, so I don't think I have to deal with that much. However, I see that there are cache folders for other programs, and I wish to know if there is a safe way to remove the cache.

Generally, my question revolves around why I have only less than 300 MB on my 4.0 GB USB thumb drive when I only use it for browsing and simple development in python.

Your help is appreciated.

share|improve this question
I face the same problem: had a 1Gb flash drive and was suffering from lack of disk space (but Ubuntu was booting, at least). Now, using a 4Gb flash drive (capped to ~2Gb, as discussion) I'm facing the same problems, although I managed to install Java beyond booting. Something is definitely eating out disk. – Tiago Cardoso Dec 26 '15 at 18:55
If it helps, using df -Th I can see /cow using 100% of available disk space. Question then should be... is it something that could be re-dimentioned? – Tiago Cardoso Dec 26 '15 at 21:37
for the point '2.', simply call apt clean functionality, his goal is to clean /var/cache/apt content : sudo apt-get clean – adrenochrome Feb 19 at 9:31
up vote 0 down vote accepted

You would need to make a custom .iso to modify those files.

See : Can I build a Ubuntu ISO from a manifest?

The root file system is compressed to fit on the iso, but casper mounts the file system ro (rofs).

You can use persistence , but persistence takes up even more space (cow).

How did you make your usb ? The iso should take up only 700 Mb or so, do you have other data stored on the usb ? Persistence ?

share|improve this answer
I have persistent storage (casper-rw) and I really just installed chromium, vlc, (I left Firefox on,) I removed big apps like Thunderbird and LibreOffice. I'm thinking that there are unused packages (like libraries) left behind from some of those uninstalls. – ladaghini Mar 18 '12 at 14:57
2.5GB is the maximum capacity, and like I said, I have like 300MB remaining. – ladaghini Mar 18 '12 at 15:29
2.5 GB is the maximum capacity, which, as I said earlier, I was reaching. What I would like to know is what is filling up that 2.5 GB (which used to be 2.0, but I added another 512 MB) As far as I am concerned, I have fewer programs installed (space usage wise) than a fresh live USB. And yet, even after adding another 512 MB, I have a measly 300 MB left. There must be some useless files just lurking around. – ladaghini Mar 19 '12 at 14:59
The files on the iso are read only, you can not delete them. A cow file system makes a copy of the files and tracks the changes, so it takes a lot of space. Again, you need to either remaster the iso or perform a standard installation, but persistence does not work they way you think it does, thus it is not behaving as you expect. – bodhi.zazen Mar 19 '12 at 15:39

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