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Bash truncates HISTFILE when disk is full

From: chkno
Subject: Bash truncates HISTFILE when disk is full
Date: Sun, 20 Mar 2011 19:37:40 -0700
User-agent: Mutt/1.5.20 (2009-06-14)

Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i686' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I../bash -I../bash/include -I../bash/lib   -g -O2 -Wall
uname output: Linux dragonfly 2.6.35-27-generic #48-Ubuntu SMP Tue Feb 22 
20:25:29 UTC 2011 i686 GNU/Linux
Machine Type: i686-pc-linux-gnu

Bash Version: 4.1
Patch Level: 5
Release Status: release

        Bash truncates HISTFILE (~/.bash_history) to zero bytes when the
        filesystem is full.

        Use bash with a full HISTFILE (ie, one that has HISTFILESIZE lines
        in it) and a full disk.  The HISTFILE is empty afterwords.

        Long, drawn out, concrete example including making a new test
        user with a home directory on a separate filesystem so it can
        be easily and harmlessly filled up:

        $ # Create a new user with a home dir on a small temporary filesystem
        $ sudo adduser bashbug
        Adding user `bashbug' ...
        Adding new group `bashbug' (1002) ...
        Adding new user `bashbug' (1002) with group `bashbug' ...
        Creating home directory `/home/bashbug' ...
        Copying files from `/etc/skel' ...
        Enter new UNIX password:
        Retype new UNIX password:
        passwd: password updated successfully
        Changing the user information for bashbug
        Enter the new value, or press ENTER for the default
                Full Name []:
                Room Number []:
                Work Phone []:
                Home Phone []:
                Other []:
        Is the information correct? [Y/n]
        $ dd if=/dev/zero of=/dev/shm/bashbug-home bs=1M count=10
        10+0 records in
        10+0 records out
        10485760 bytes (10 MB) copied, 0.0332525 s, 315 MB/s
        $ mke2fs /dev/shm/bashbug-home
        mke2fs 1.41.12 (17-May-2010)
        /dev/shm/bashbug-home is not a block special device.
        Proceed anyway? (y,n) y
        Filesystem label=
        OS type: Linux
        Block size=1024 (log=0)
        Fragment size=1024 (log=0)
        Stride=0 blocks, Stripe width=0 blocks
        2560 inodes, 10240 blocks
        512 blocks (5.00%) reserved for the super user
        First data block=1
        Maximum filesystem blocks=10485760
        2 block groups
        8192 blocks per group, 8192 fragments per group
        1280 inodes per group
        Superblock backups stored on blocks:

        Writing inode tables: done
        Writing superblocks and filesystem accounting information: done

        This filesystem will be automatically checked every 31 mounts or
        180 days, whichever comes first.  Use tune2fs -c or -i to override.
        $ sudo mount -o loop /dev/shm/bashbug-home /dev/shm/bashbug-home-mnt
        $ sudo mv -v /home/bashbug/* /home/bashbug/.??* 
        `/home/bashbug/examples.desktop' -> 
        removed `/home/bashbug/examples.desktop'
        `/home/bashbug/.bash_logout' -> `/dev/shm/bashbug-home-mnt/.bash_logout'
        removed `/home/bashbug/.bash_logout'
        `/home/bashbug/.bashrc' -> `/dev/shm/bashbug-home-mnt/.bashrc'
        removed `/home/bashbug/.bashrc'
        `/home/bashbug/.profile' -> `/dev/shm/bashbug-home-mnt/.profile'
        removed `/home/bashbug/.profile'
        $ sudo chown bashbug:bashbug /dev/shm/bashbug-home-mnt
        $ sudo umount /dev/shm/bashbug-home-mnt
        $ sudo mount -o loop /dev/shm/bashbug-home /home/bashbug
        $ df
        Filesystem           1K-blocks      Used Available Use% Mounted on
        /dev/loop0                9911        99      9300   2% /home/bashbug
        $ # Fill up .bash_history and let bash trim it to HISTFILESIZE
        $ sudo -u bashbug -i
        bashbug$ yes | head -n 3000 > .bash_history
        bashbug$ echo $HISTFILE $HISTSIZE $HISTFILESIZE  # The defaults
        /home/bashbug/.bash_history 1000 2000
        bashbug$ wc -l .bash_history
        3000 .bash_history
        bashbug$ logout
        $ wc -l /home/bashbug/.bash_history
        2000 /home/bashbug/.bash_history
        $ # Fill up the filesystem
        $ sudo bash -c 'yes > /home/bashbug/full'
        yes: standard output: No space left on device
        yes: write error
        $ # On next use, .bash_history becomes empty:
        $ sudo -u bashbug -i
        bashbug$ whoami  # Any command
        bashbug$ logout
        $ ls -l /home/bashbug/.bash_history
        -rw-r--r-- 1 bashbug bashbug 0 2011-03-20 17:08 

        Bash should write out the new HISTFILE before destroying the
        existing one.  That way, if writing the new one fails, the old
        one can be left intact.

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