Vidul Nikolaev Petrov » SA

Delete All Directories Except

Vidul — Sat, 27 Mar 2010 00:20:04 +0000

Write a Bash function or an alias.

#######
### alias 
#######
alias _rm_except="rm -rf $(ls | grep -v ^$1$)"
 
##########
### function
##########
_rm_except () { rm -rf $(ls | grep -v ^$1$) }
 
# sample usage:
$ cd /tmp && mkdir 1 2 3 11 22 33
$ _rm_except 1; ls
11  2  22  3  33

Automation of Systems Administration Tasks

Vidul — Sun, 31 Jan 2010 08:25:45 +0000

No need for complex, unclear, and clumsy programs like Capistrano.

Use Fabric, here is a short exmple, which automates the archive process of users’ directories:

 
# install the Python library
easy_install fabric
 
# create a file called "fabfile"
# it will be used from the "fab" command
# add the following tasks in "fabfile":

from fabric.api import *
 
env.hosts = ["main"]
env.user  = "root"
 
 
def archive_home():
  with cd("/tmp"):
   run("zip -rq home_`date +%Y:%m:%d-%H:%M`.zip /home")
 
def archive_download():
  import os
  os.system("scp %s:/tmp/home_*.zip /home/su/archive" % env.hosts[0])
 
def archive_remove():
  run("rm /tmp/home_*.zip")

In addition you can use decorators to specify different hosts for different tasks.

More about the “fab” command:

fab --help
Usage: fab [options] (command) [:arg1,arg2=val2,host=foo,hosts='h1;h2',...] ...
 
Options:
  -h, --help       show this help message and exit
  -V, --version  show program's version number and exit
  -l, --list           print list of possible commands and exit
  -d COMMAND, --display=COMMAND
                        print detailed info about a given command and exit
  -r, --reject-unknown-hosts
                        reject unknown hosts
  -D, --disable-known-hosts
                        do not load user known_hosts file
  -u USER, --user=USER  username to use when connecting to remote hosts
  -p PASSWORD, --password=PASSWORD
                        password for use with authentication and/or sudo
  -H HOSTS, --hosts=HOSTS
                        comma-separated list of hosts to operate on
  -R ROLES, --roles=ROLES
                        comma-separated list of roles to operate on
  -i KEY_FILENAME       path to SSH private key file. May be repeated.
  -f FABFILE, --fabfile=FABFILE
                        name of fabfile to load, e.g. 'fabfile.py' or
                        '../other.py'
  -w, --warn-only       warn, instead of abort, when commands fail
  -s SHELL, --shell=SHELL
                        specify a new shell, defaults to '/bin/bash -l -c'
  -c RCFILE, --config=RCFILE
                        specify location of config file to use
  --hide=LEVELS           comma-separated list of output levels to hide
  --show=LEVELS         comma-separated list of output levels to show

ssh fails silently on key authentication

Vidul — Wed, 20 Jan 2010 15:47:04 +0000

If it happens that only root (or no one) can use key authentication, most probably the permissions are wrong. Check the following permissions:

ls -ld ~/.ssh | awk '{print $1}'
# should return drwx------
# otherwise: chmod 0700 ~/.ssh

socket.error: (99, ‘Cannot assign requested address’)

Vidul — Sun, 27 Dec 2009 20:07:09 +0000

Enable the localhost interface:
/sbin/ifconfig lo up

`mkdir` and `cd` at once

Vidul — Wed, 16 Dec 2009 10:50:39 +0000

I am sick of mkdir dir_name; cd dir_name;
The solution (put this function in “.bashrc” or whatever shell config file you use):

_mkcd () {
       mkdir -p $1
       cd $1
}
# usage: _mkcd /tmp/dir_1/dir_2
# pwd will show: /tmp/dir_1/dir_2

unarchive files

Vidul — Mon, 14 Dec 2009 19:31:21 +0000

a sample BASH function (usually resides in $HOMES/.bashrc)

extract () {
        if [ -f $1 ] ; then
                case $1 in
                        *.tar.bz2) tar xjf $1;;
                        *.tar.gz) tar xzf $1;;
                        *.bz2) bunzip2 $1;;
                        *.rar) rar x $1;;
                        *.gz) gunzip $1;;
                        *.tar) tar xf $1;;
                        *.tbz2) tar xjf $1;;
                        *.tgz) tar xzf $1;;
                        *.zip) unzip $1;;
                        *.Z) uncompress $1;;
                        *) echo "'$1' cannot be extracted via extract()";;
                esac
        else
                echo "'$1' is not a valid file"
        fi
}

iptables – blocking incoming traffic

Vidul — Sat, 14 Feb 2009 16:28:00 +0000

This iptables config will block all incoming traffic, except from machines, identified by thier MAC addresses:

iptables -F INPUT

iptables -A INPUT -m mac—mac-source 00:3f:5f:ab:2c:7d -j ACCEPT

iptables -A INPUT -m mac—mac-source 00:1e:32:36:97:4a -j ACCEPT

iptables -A INPUT -m mac—mac-source 00:44:11:a5:1d:6d -j ACCEPT

# or by ip address:

#iptables -A INPUT -p tcp -s 1.1.1.1 -j ACCEPT

#iptables -A INPUT -p tcp -s 2.2.2.2 -j ACCEPT

#iptables -A INPUT -p tcp -s 3.3.3.3 -j ACCEPT

iptables -A INPUT -m state—state ESTABLISHED -j ACCEPT

iptables -A INPUT -s 127.0.0.1 -j ACCEPT

iptables -A INPUT -j REJECT

PS1 colors

Vidul — Sat, 14 Feb 2009 09:11:00 +0000

I like to see green prompt for userid > 0 and red for root, also the hostname and the history number of a command.

PS1="\[\e[32;1m\]\u\[\e[30;1m\]@\[\e[32;1m\]\H[\!]\W\[\e[30;1m\]\\$\[\e[0m\]"

PS1="\[\e[32;1m\]\u\[\e[30;1m\]@\[\e[32;1m\]\H[\!]\W\[\e[30;1m\]\\$\[\e[0m\]"

how to monitor ip addresses from a log file

Vidul — Thu, 29 Jan 2009 00:12:00 +0000

tail -f production.log  | egrep "([[:digit:]]{1,3}\.){3}[[:digit:]]{1,3}"

Security Problems with KDE

Vidul — Sun, 18 Jan 2009 09:39:00 +0000

From tcpdump it becomes obvious that some kde apps are contacting jamaica.kde.org through http!?
I cannot understand this M$ type of behavior in UNIX env, neither I want , so here is a quick solution:

iptables -A OUTPUT -d 62.70.27.118 -p tcp -j DROP
iptables -A OUTPUT -j ACCEPT