Understanding LINUX commands.
1. man
Command:
The best source of information for most commands can
be found in the online manual pages, known as “man pages” for short. To read a
command's man page, type “man command”.
Syntax:
man
<command>
Example:
man
ls
Get help on the “ls” command.
2. Using a
Command's Built-In Help:
Many commands have simple “help” screens that can be
invoked with special command flags. These flags usually look like “-h” or
“--help”.
Example:
ls
--help
3. cat
Command:
“cat” is short for concatenate. This command
is used to create, view and concatenate files.
Syntax:
cat [argument] [specific file]
Example1: cat
> filename
This
command is used to creating a file with the given filename.
Example2: cat
filename
This
command is used to view the contents of given filename.
Example3: cat
file1 file2 > file3
This command combines the contents of the
file1 and file2 into file3.
4. pwd
Command:
"pwd" stands for present working
directory. It displays your current position in the UNIX file system.
Syntax:
pwd
Example:
pwd
There are no options (or arguments) with the
"pwd" command. It is simply used to report your current working
directory.
5. ls
Command:
"ls"
stands for list. It is used to list information about files and directories.
Syntax: ls [options] [names]
Examples:
ls
This is the basic "ls" command, with no options. It provides
a very basic listing of the files in your current working directory. Filenames
beginning with a decimal are considered hidden
files, and they are not shown.
ls -a
The -a option tells the ls command to report information about all
files, including hidden files.
ls -l
The -l option tells the "ls" command to provide a long listing of information about the
files and directories it reports. The long listing will provide important
information about file permissions, user and group ownership, file size, and
creation date.
6. mkdir
Command:
mkdir
stands for make directory. This command is used to create a directory.
Syntax: mkdir
directory_name
Example: mkdir
mydirectory
7. cd
Command:
cd
stands for Change Directory.
Syntax: cd
When
typed it returns you to your home directory.
Syntax: cd
directory
Change
into the specified directory name.
8. cp
Command:
Copies
a file from one location to another.
Syntax: cp
file_name directory
Example:
cp myfile.txt /mydir
Copies
the myfile.txt file to the /mydir directory
9. mv
Command:
Moves
a file to a new location, or renames it.
Syntax: mv
file_name directory
Example: mv
myfile1.txt /mydir
Copy
the file to /mydir, and delete it from the original location.
Syntax: mv
old_filename new_filename
Example:
mv myfile1.txt myfile2.txt
Rename
myfile1.txt to myfile2.txt.
10. rm Command:
This
command is used to delete a file.
Syntax: rm
filename
Example:
rm myfile.txt
Removes
myfile.txt file.
11. rmdir Command:
This
command is used to remove an empty directory.
Syntax: rmdir
dir_name
Example:
rmdir mydir
Removes mydir
directory if the directory is empty only.