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Creating files in Unix

File Creation:

We can create files in 3 different ways.

1. touch
2. cat
3. vi editor

CAT: With the help of  cat command we can create the files, we can add data to the existing file or create a file but we cannot manipulate the data to the file.

Example: # cat <filename>

# cat _>filename <enter content here without brackets>

Add data to existing file

#cat >>file name

Display the file with line numbers

#cat -n filename

Note: when we a create a file with existing data, then the previous data will be overwritten with the existing.

Touch: With the help of touch command we can create a number of files with zero bytes. It cannot append the data to the existing / creating file.

Ex:  # touch test test1 test2 test3

four files created which are test, test1, test2 and test3 in present directory.

checkout # ls  -l

VI Editor:  This is one of the powerful tool.

It has three types

1. Insert mode
2. insert mode
3. colon mode

Insert Mode:

Key combinations:

Cursor Moving commands:

Delete commands:

Copy commands:

Replace commands:

Colon mode commands:

use it with esc+shift+:

example: esc+shift+:w to save the file

SHELL

SHELL: Is a between user and Kernel. Shell is a Command checker.

Kernel: Kernel will control all the system applications.

Types of Shells:

In Unix we have five types of Shells.

#echo $ – it displays the present working shell (except C shell)

#echo $shell – it is for C shell

#echo $SHELL – it displays the default shell

File Systems – Solaris

• / indicates root directory
• /bin contains normal user commands
• /sbin contains system admin commands
• /var contains log file information
• /etc contains all configuration files
• /devices contacins physical devices information
• /dev contains logical device information which belongs to physical device info
• /proc contains process id information
• /opt contains 3rd party packages information
• /kernel contains kernel module information
• /home default home directory of a normal user
• /tmp temporary file information
• /usr man page command

Unix basic commands

Unix Basic commands

Note:  files system of unix supports case sensitive.

ls: it displays list of directories and files.

ls -f : to justify files and directories (or called as folders)

ls -F: to show only directories

Note:  if there is / symbol then it is a directory and all files without any dot extension are text files.

Example: home/ , Documents/

@ symbol indicates linked files or linked directories.

ls -a : lists hidden files and directories also.

ls -aF : justify hidden files and directories.

ls -i : it displays inode number of files and directories

ls -l : it displays with long list format. It also gives information of no. of files and 7 fields.

• first part of the first field starts with either l , d or -

l – indicates linked file or directory

d – indicates directory

-   -indicates normal text files

• second field contains number of links to the files and directories
• Third field contains user ownership
• fourth field contains group ownership
• fifth field shows size of file or directory
• sixth field shows date and time of the file created or modified
• Seventh Field shows file or directory name.

pwd command displays the present working directory, the directory which you are currently logged in

cd – change directory

example: if your are in home directory /home or /export/home to go to another directory use cd command

# cd  /

# cd  /Documents

note: you cannot go to hierarchy directory ie: if your pwd is /home ,  and you want to go to /Documents directory, you cannot jump to directory above home dir. First go to root dir (/) and then use command cd  /Documents