df

df is it displays the amount of disk space available on the filesystem containing each file name argument

cal

cal displays the date so for instance here it shows September 17, 2014

free

free displays the amount of memory is being used and not used

 

 

cd

cd means change directory allowing the program to change the current working directory in the operating system    

pwd

pwd means what current working directory its on

ls

ls shows command that lists directory contents of files and directories

file

file determines which file type it is on

less

less allows backward movement in the file as well as forward movement

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