Linux Basic Commands

Advanced Linux Commands

1. How to create large file a TXT of 1GB for testing purposes by linux command?

$dd if=/dev/zero of=file.txt count=1024 bs=1048576

1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 17.1951 s, 62.4 MB/s

 

 

2. To see if the Ubuntu machine is 32 or 64 bit

#uname -a

• for 32bit: Linux frobov-komp 3.2.0-63-generic #95-Ubuntu SMP Thu May 15 23:06:36 UTC 2014 i686 i686 i386 GNU/Linux
• for 64bit: Linux discworld 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:50 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

 

 

#uname -m

i686

 

 

3. Modifing long bash prompt

For example: frob@frobov-komp:/homemiko/com_webdevelopment-tutorials/www/public_html/code/smiko/database$

 

PS1=\\u@\\h\ \\w\\n\\$\    -prompt in separate line

PS1="\u - \W $ "   gives only frob - mongodb$

 * \a : an ASCII bell character (07)
    * \d : the date in "Weekday Month Date" format (e.g., "Tue May 26")
    * \D{format} : the format is passed to strftime(3) and the result is inserted into the prompt string; an empty format results in a locale-specific time representation. The braces are required
    * \e : an ASCII escape character (033)
    * \h : the hostname up to the first '.'
    * \H : the hostname
    * \j : the number of jobs currently managed by the shell
    * \l : the basename of the shell’s terminal device name
    * \n : newline
    * \r : carriage return
    * \s : the name of the shell, the basename of $0 (the portion following the final slash)
    * \t : the current time in 24-hour HH:MM:SS format
    * \T : the current time in 12-hour HH:MM:SS format
    * \@ : the current time in 12-hour am/pm format
    * \A : the current time in 24-hour HH:MM format
    * \u : the username of the current user
    * \v : the version of bash (e.g., 2.00)
    * \V : the release of bash, version + patch level (e.g., 2.00.0)
    * \w : the current working directory, with $HOME abbreviated with a tilde
    * \W : the basename of the current working directory, with $HOME abbreviated with a tilde
    * \! : the history number of this command
    * \# : the command number of this command
    * \$ : if the effective UID is 0, a #, otherwise a $
    * \nnn : the character corresponding to the octal number nnn
    * \\ : a backslash
    * \[ : begin a sequence of non-printing characters, which could be used to embed a terminal control sequence into the prompt
    * \] : end a sequence of non-printing characters

 

If you want permanently change your prompt edit ~/.bashrc file :

In Ubuntu 12.04

# PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
PS1="\u - \W $ "

After that restart with $source ~/.bashrc  or just  $ . ~/.bashrc

 

 

 

4. Midnight Commander

 Midnight commander is a file browser like Norton Commander .

#apt-get install mc

Start Midnight commander with #mc .