Commands

Manipulating files

Commands that can be used for reading and manipulating files

tail

tail by default reads the last 5 lines of the input file and then exits

Useful Flags    Function
-n *x*          Returns the last x lines of a file
-f              Follows the end of the file, so any new data will be printed out to the screen

head

head by default reads the first 5 lines of the input file and then exits

Useful Flags        Function
-n *x*              Returns the first x lines of a file

awk

awk is used to extract, layout and modify data using the command line (It is way more then this but its all I use it for)

sed

sed is the 'Stream EDitor' you can use to to modify files via commands and scripts using patterns, an example can be seen here

Useful Flags        Function
-i                  In-place, writes the changes to the file
-f                  Use a script file instead of reading the expression from STDIN

grep

grep is used to match text in a file,

Useful Flags    Function
-o              Returns only the matched data (Useless without regex really)
-E              Allows extended regex to be used in the search, [regex info](/regex)
-P              Allows the use of Perl regex, this uses a different syntax to -E
-i              Makes the search case insensitive
-r              Searches files recursively (i.e if you have quite a few files and folders it will search through all of them)
-l              Returns the filename where the data was matched instead of the matched data

Some examples of grep usage can be found here

lsof

lsof is a command that will show you what processes have specified file open currently you can see an example here

Manipulating the standard input

These commands can be used to manipulate data in the standard input

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