Unix Shell Scripting :
We interact with the Unix kernel with the help shell application (which is called Terminal)
All unix commands have to be in lower case.
clear : clears the screen
cd ~ : Navigate to root folder
who am I : displays three colums ( username, terminal id, time and date of login)
pwd : shows the directory where the shell is in. (pwd stands for present working directory)
cal : shows the calendar of the current month and year and current date is highlighted
cal 8 2007 or cal aug 2007 : calendar of august 2007 will be displayed
date : displays the date ( displays in default format)
To display date in custom format , then we do in the following way
date ‘+DATE: %m-%y%Ntime:%H%M%S’ :
if you observe in the above command we have written in capital letters, that is not a command,that is to define format , so it can be written in capital letters
touch file1 file2 : this commands creates files in home directory
mkdir testdir : creates a directory with name testdir in the home directory
mkdir documents/testdir : creates a directory in the documents path
cd testdir : changes the present working directory to the testdir , to create a file and content
cat > test : write the contents of the file, ctrl + D to end the editing
cat < test : to show the contents of the file.
Merge two files cat > file1 file2 > file3 : contents of file1 and file2 will be merged and copied into file3
Rename and Delete :
mv oldfilename newfilename : this renames the file or dire to new name given
rm filename : file will be deleted
rm –r directoryname : to deleted the directory
rmdir directoryname : also deleted the directory
Copies :
cp file_to_be_copied destinationpath : copies the file to the destination path
Links
Hardlinks : creates a replica : ln old new :
Softlinks : create a shortcut
File Permissions :
Every file or directory have below types of permissions
Owner
Read/Write
Group having access
Others
umask : displays the four digit no , ignore the first digit , and substract the number from 666 if it is a file and from 777 if it is a directory,
ex : if the value 0022 for a file, subtract the value from 666 which give 644, that means the owner has read and write permissions where as the group and others have just read access.
chmod : is used to modify file permissions of a file or directory
ex : chmod 666 filename : gives read and write to all for a file
We interact with the Unix kernel with the help shell application (which is called Terminal)
All unix commands have to be in lower case.
clear : clears the screen
cd ~ : Navigate to root folder
who am I : displays three colums ( username, terminal id, time and date of login)
pwd : shows the directory where the shell is in. (pwd stands for present working directory)
cal : shows the calendar of the current month and year and current date is highlighted
cal 8 2007 or cal aug 2007 : calendar of august 2007 will be displayed
date : displays the date ( displays in default format)
To display date in custom format , then we do in the following way
date ‘+DATE: %m-%y%Ntime:%H%M%S’ :
if you observe in the above command we have written in capital letters, that is not a command,that is to define format , so it can be written in capital letters
touch file1 file2 : this commands creates files in home directory
mkdir testdir : creates a directory with name testdir in the home directory
mkdir documents/testdir : creates a directory in the documents path
cd testdir : changes the present working directory to the testdir , to create a file and content
cat > test : write the contents of the file, ctrl + D to end the editing
cat < test : to show the contents of the file.
Merge two files cat > file1 file2 > file3 : contents of file1 and file2 will be merged and copied into file3
Rename and Delete :
mv oldfilename newfilename : this renames the file or dire to new name given
rm filename : file will be deleted
rm –r directoryname : to deleted the directory
rmdir directoryname : also deleted the directory
Copies :
cp file_to_be_copied destinationpath : copies the file to the destination path
Links
Hardlinks : creates a replica : ln old new :
Softlinks : create a shortcut
File Permissions :
Every file or directory have below types of permissions
Owner
Read/Write
Group having access
Others
umask : displays the four digit no , ignore the first digit , and substract the number from 666 if it is a file and from 777 if it is a directory,
ex : if the value 0022 for a file, subtract the value from 666 which give 644, that means the owner has read and write permissions where as the group and others have just read access.
chmod : is used to modify file permissions of a file or directory
ex : chmod 666 filename : gives read and write to all for a file
Contents of directory:
ls : lists the folders and files in a file of the home directory
ls directoryname :
ls - l : longlist .
ls – a : lists all the files along with hidden files
file * : displays the contents of the folder, says the type of file ,directory etc
ls –ltra (shows all the hidden files
ls –F : helps us to differentiate between files and directories
OS version details
uname –a : to now the version of the os and
Count characters, words and lines:
1.wc filenametobeevaluated : displays the no of lines, words and characters
2.wc –l filenametobeevaluated :If we want only no of line then simply use
Sorting :
sort filetobesorted : the lines in the file will be sorted
