Linux Commands - File Content Operations

I present to you a compilation of the most useful Linux commands for File Content Operations

Pipes and I/O redirection

#redirect command output to a new file
command > output_file.txt


#redirect command output to append to a file
command >> output_file.txt


#redirect command input
command < input_file.txt


#redirect standard output and error output to a file:
command &> output_file.txt


#pipe, redirect command1 output as input to command2
command1 | command2

Display file content

#display file content
echo file


#show file content
cat file


#display file content starting from the end
tac file


#display file content scrolling line by line
more file


#display file content scrolling forward or backward
less file


#display the first two lines of a file
head -2 file


#display the last two lines of a file
tail -2 file


#real-time display of the last lines of a file (tracking)
tail -f file

Text manipulation

#convert lowercase to uppercase
echo 'file' | tr '[:lower:]' '[:upper:]'


#delete lines 1 to 5 from a file
sed '3,5d' file


#delete lines 5 to the end of a file
sed '5,$d' file


#delete blank lines
sed '/^$/d' file


#delete blank lines and comments
sed '/ *#/d; /^$/d' file


#replace one string with another
sed 's/string1/string2/g' file 
  

#display only the lines that contain a string
sed -n '/string/p'