Useful commands Linux

Useful commands Linux

Some tasks may require the skills of working with the Linux command line. This is easy enough if you know the basic commands which Linux-server understands.

Interaction with the server takes place via SSH protocol, so if you are running Microsoft Windows, you will need to install a program to work with SSH (Linux and Mac OS doesn’t require additional installations):

• PuTTY - free program for working with SSH, which doesn’t require installation.
• ExtraPuTTY - an enhanced version of PuTTY.
• SecureCRT - a powerful program to work with SSH (supports many other protocols).

Keyboard shortcuts

• Ctrl + C - stops the current command.
• Ctrl + D - log out (similar to exit).
• exit - log out.
• Ctrl + W - erases one word in the current line.
• Ctrl + U - delete line.
• !! - Repeat the last command.

Other useful commands

Upload file to server:

wget http://www.cloudhosting.lv/filename.zip

Processes list:

top

Processes list of a certain user:

top –u user-name

Currnet date:

date

Change password:

passwd

Change password of a certain user:

passwd user-name

Show information about core:

uname -a

Show information about CPU:

cat /proc/cpuinfo

Show information about memory:

cat /proc/meminfo

Show information about disc usage:

df

Restart certain service:

/etc/init.d/service-name restart

Information about memory usage and swap:

free

Possible application location:

whereis application-name

Server restart (full reboot):

Reboot

Archiving / Unzipping

Create tar.gz-archive:

tar czf archive-name.tar.gz directory-name 

Unpack the tar.gz-archive:

tar xzf archive-name.tar.gz 

Create tar.bz2-archive:

tar cjf archive-name.tar.bz2 directory-name 

Tar.bz2-unpacking archive:

tar xjf archive-name.tar.bz2 

Unpack the rar-archive:

unrar x archive-name.rar

Working with files and folders

List of files and folders:

ls 

Full list of files and folders, including hidden:

ls -a 

Change directory:

cd directory-name

Examples of use:

• cd / - move to the root directory of the disk;
• cd .. - move to the upper directory;
• cd ../ .. – move to the 2 upper directories;
• cd $ HOME - move to the home directory (just enough to type cd);
• cd /home/folder-name/subfolder-name - go to the specified folder.

Create folder:

mkdir folder-name

Delete folder or file:

rm file-name

Delete files and folders recursively (including all attached files and folders):

rm -r folder-name

Copy file:

cp file-name copy-file-name

Copy folder:

cp -r folder-name copy-folder-name

Rename file:

mv file-name new-file-name

If «new-file-name» — is a folder, file will be moved to its folder.

Create symbolic link:

ln -s file-name link-name

Change permission (CHMOD) to file or folder:

chmod 755 folder-name

Change permission (CHMOD) to all files recursively:

find . -type f | xargs chmod 644

Change permission (CHMOD) to all files with specific extension recursively:

find . -name '*.cgi' -type f | xargs chmod 755

Change permission (CHMOD) to all folders recursively:

find . -type d | xargs chmod 755

Data base backup

Data base backup with mysqldump (command must be in one line):

mysqldump --user=USERNAME --host=HOST -acnqQ --single-transaction
 --default-character-set=ENCODING --password=PASSWORD -- DATA_BASE
 | sed s#^CREATE TABLE# IF NOT EXISTS# ; s#^INSERT INTO#REPLACE INTO#
 | gzip -qf9c > /home/username/directory-where-backups-will-be-stored/data-base-name-
`date +%Y-%m-%d`.sql.gz

Encoding example: cp1251, utf8.

Working with Perl

Performing Perl-script:

perl script-name.cgi

Perl module installation through CPAN:

install MODULE: :NAME

Before doing this you must enter into CPAN, entering next command:

perl -MCPAN -e shell