Linux Tips

Disable Auto-Mount

You can temporarily disable automount by doing as root [1]:

$ rcdbus stop

Fast Copy

Using Netcat

When copying a directory that contains a lot of small files (like 1000+ files <1kB), it is faster to actually generate a tarball of the directory and have it unpacked on the fly on the destination server [2]:

# On DESTINATION box, launch first the listener
nc -l -p 2342 | tar -C /target/dir -xzf -
#On SOURCE box, launch the sender
tar -cz /source/dir | nc -w 3 Target_Box 2342

Using tar

Say you want to copy from directory /mnt/img to /mnt/usb

(cd /mnt/img ; tar -cf - *) | (cd /mnt/usb ; tar -xvf -)
sync                                                         # Flush file system buffers

Other

See here

Fast Search

Locate

! Power Tip ! Use locate to find files rapidly by their names. locate is very lightweight (hardly notice it's running) and very efficient. It works for any file in any local file system.

Recoll, Beagle, Google Desktop...

See Linux Software for more powerful search tool (searching in file content).

Password prompt during boot

This is a tip for GDM but similar tip works for KDM. It prompts for a password needed to mount a password protected HOME partition [3].

Add at the end of /etc/gdm/Init/Default:

DEVICE=/dev/sda6
while [ ! -e /dev/mapper/cryptohome ]; do
zenity --entry --hide-text --text="Enter your passphrase:" | cryptsetup luksOpen $DEVICE cryptohome
done
mount /dev/mapper/cryptohome /home

Open File Manager at Current Directory from Terminal

Source [4]

xdg-open .               # Works for any desktop
gnome-open .             # In Gnome
nautilus .               # Open Nautilus specifically

Fix 'Permission denied' when removing (rm) a file as root

We try to remove a file as root but get an Operation not permitted error. How is that possible?

ls -l
# -rw-r--r-- 1 root root 144 Mar 14 07:33 extlinux.conf
# -r-------- 1 root root 60K Mar 14 07:06 ldlinux.sys
rm ldlinux.sys
# rm: cannot remove ‘ldlinux.sys’: Operation not permitted

Two possibilities:

• The immutable file attribute is set
• The filesystem is mounted read-only.

In the latter case, just mount the filesystem with write access. In the former case, use chattr:

lsattr ldlinux.sys
# ----i----------- ldlinux.sys
chattr -i ldlinux.sys
rm ldlinux.sys