Synopsis: ./removedups.sh addresses.txt > tempaddress.txt

#!/bin/bash

cat "$@" | {
awk '!x[$0]++'
}


You have a file users.txt with the ff:

xyzn9512
hchu4814
pjfs9418
ntxt5325
cajg6747
jexg3621
xfay1986
krkl5696

And want to append @domain.com. Just do the ff:

sed 's/$/@domain.com/' users.txt

This will result of the ff:

xyzn9512@domain.com
hchu4814@domain.com
pjfs9418@domain.com
ntxt5325@domain.com
cajg6747@domain.com
jexg3621@domain.com
xfay1986@domain.com
krkl5696@domain.com


Just dump it to a new text file if you want to have a record of the output.

On an Alpha hosts:
> ssh -V
ssh: SSH Secure Shell 3.1.0 (non-commercial version) on alpha-dec-osf5.1

On a linux host:
> ssh -V
OpenSSH_3.1p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f

Method for OpenSSH local to OpenSSH remote

1. Local host; top level of your home directory; create the key pair:

[OpenSSHhost]> ssh-keygen -t dsa
Generating public/private dsa key pair.
Enter file in which to save the key (/yourhomedir/.ssh/id_dsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /yourhomedir/.ssh/id_dsa.
Your public key has been saved in /yourhomedir/.ssh/id_dsa.pub.
The key fingerprint is:
03:aa:71:.......etc.........:94 username@local.met.tamu.edu

This is the creation of a dsa key pair (see ssh man pages). It has asked for a passphrase, which is a second-level password encoded in the private key and represents additional security (see ssh man pages). It will be prompted for on login unless it is left blank, which we do here.
Note that the private and public keys, stored in files id_dsa and id_dsa.pub, respectively, are written to a directory at the top level of your home directory called ‘.ssh’. That is also where the host keys are stored for remote hosts that you have logged into, in a file called known_hosts. The private key file, id_dsa, is created without group or other’s permissions to read, write, or execute. Leave it that way — no one must have access to that key; don’t copy it anywhere else or give to anyone else. The public key file, id_dsa.pub, may be readable by others, but you may remove that if you like; they really can’t do anything harmful with it except maybe add it to their authorized_keys file, which gives you auto login to their account without having to provide their password!

2. Login (ssh) to the remote host and add the local public key to a file called authorized_keys in the .ssh directory on the remote host:

[OpenSSHhost]> ssh remoteOpenSSHhost
username@remoteOpenSSHhost's password:
[remoteOpenSSHhost]> cd .ssh
[remoteOpenSSHhost]> cat id_dsa.pub >> authorized_keys
username@OpenSSHhost's password:

3. Change permission for securirty purposes

chmod 700 .ssh
chmod 600 .ssh/authorized_keys

You can list the contents of authorized_keys to confirm that the key was added. Note that we used the concatenate redirection, >>, to add the key to authorized_keys, because you want to keep any other keys you may have similarly added for auto loggins from other hosts.
Now back on the local machine, you should be able to ssh to the remote host and it will log you in without prompting for the password on the remote host.
Repeat step 2 on each remote host that you wish to be able to achieve such automatic login from this local host

2. Method for OpenSSH to SSH-SS

SSH-SS has a different format for the public key. We need to convert the local OpenSSH public key to that format, then add it to the authorized_keys file on the remote SSH-SS host.

1. local OpenSSH host; cd to .ssh directory and generate private-public key pair as in step 1, above, if not already done.

2. convert OpenSSH public key to SSH-SS style public key:

[OpenSSHhost]> ssh-keygen -e -f id_dsa.pub > sshss_dsa.pub [this output filename is arbitrary]

3. ssh login to SSH-SS host; cd to .ssh2 in top level of home directory

[SSH-SShost]> cd .ssh2
[SSH-SShost]> cat sshss_dsa.pub >> authorized_keys

Make sure permissions mode for authorized_keys is 644 (-rw-r–r–)

4. create file authorization and add “Key authorized_keys” to it:

[SSH-SShost]> echo "Key authorized_keys" > authorization

Now, try the auto login from the OpenSSH to the remote SSH-SS host

double quote:”, the
forward quote: ‘, and the
back quote: `.

Does each of them mean something? Yes

The double quote is used mainly to hold a string of words and preserve whitespace.

For instance, “This string contains whitespace.”. A string enclosed in double quotes is treated as one argument.

For instance, take the following examples:

[nelson@cacti ~]$ mkdir "hello world"
[nelson@cacti ~]$ ll
total 16
drwxrwxr-x 2 nelson nelson 4096 Jul 21 09:48 hello world

#!/bin/bash
x=5 # initialize x to 5
# use double quotes
echo "Using double quotes, the value of x is: $x"
# use forward quotes
echo 'Using forward quotes, the value of x is: $x'

Back quotes are completely different from double and forward quotes. They are not used to preserve whitespace. If you recall, earlier on, we used this line:

x=$(expr $x + 1)

As you already know, the result of the command expr $x + 1 is assigned to variable x. The exact same result can be achieved with back quotes:

x=`expr $x + 1`

If you want to make a hotcopy from your SQL database instead of a dump to a text file, you can use the mysqlhotcopy tool. This tool locks a table, copy it and than unlocks it again.

Use this command if you want to transfer the MySQL data to an other place on the same server.

mysqlhotcopy --user={username} --password={password} {database} {path}

Example:

mysqlhotcopy --user=root --password=xxxxxx radius /data/

This means I backing up the radius database and saving it to /data directory. If you want to restore the database, simple copy the backup file to your database directory. If your using rpm, it was mostly located at /var/lib/mysql. Just put the directory radius there and restart mysql.

Use this command if you want to transfer the MySQL data to an other server with SSH

mysqlhotcopy --method=scp --user={username} --password={password} {database} {ssh-username}@{ssh-server}:{path}

tar: Removing leading `/' from

If your parameters is like these:

tar -cjf backup.tar.bz2 /var/www

Then, change it to this:

tar -cjPf backup.tar.bz2 /var/www

No more warning message will appear.

Done this to my backup script and takes me an hour to discover the solution. Hopefully, it will not happen to you.

alter table orgs change o_id org_id int(11);
alter table orgs change o_name org_name varchar(64);
rename table orgs organizations;


Make sure you have proper permission to alter your table.

Before:

[mysqld]
port = 3306
socket = /var/lib/mysql/mysql.sock
log-bin
server-id = 9
skip-innodb

To:

[mysqld]
port = 3306
socket = /var/lib/mysql/mysql.sock
log-bin
server-id = 9
skip-innodb
datadir=/data # MY NEW PARTITION

Then start mysql. Make sure your database was already in the /data before you start up the mysql