linux add line to beginning of file

Here is my sample file # cat /tmp/file Line One Line Two Line Three Line Four Line Five . If you need to add a line to a file in Linux, and you need to add that line in a specific position of the file there is an easy solution, even if you need to do it to hundreds of thousands of files. In the following script, an existing file, books.txt is assigned to the variable, filename, and a string value will be taken as input from the user to add at the end of the file. To add a single line of text, enter: printf ‘First line of text\n’ test5.txt. To extract lines one to four, we type this command: sed -n '1,4p' coleridge.txt. echo "$(echo 'task goes here' | cat - todo.txt)" > todo.txt It's impossible to add lines to the beginning of the file without over writing the whole file. You can use the cat command on either of these files to display their contents. Add character at the beginning of each line using sed command. If the input value is not empty, then the ‘echo’ command will append the value into the books.txt file by using ‘>>’ symbol. The p means “print matched lines.” By default, sed prints all lines. To add two lines of text, separate each line with the \n option: printf ‘First line of text\n Second line of text’ test6.txt. So, the lines will be added to the file AFTER the line where condition matches. You can load it all into memory and write it back out to the file. Add a line in a specific position with Linux. And it goes without saying that the most popular command line tools for this in Linux are sed and awk – the two best text processing programs.. In the following article, you’ll find an information about how to add some text, character or comma to the beginning or to the end of every line in a file using sed and awk. Note the comma between 1 and 4. But the issue with this command is that it is appending the first line of the file and traversing entire file. Append a prefix in front of every line of a file. If the text file is small enough to fit in memory, you don't have to create a temporary file to replace it with. From time to time it is required to modify some file very fast. To start the editor in a Linux system, type vi followed by the name of the file you want to edit, like this: vi /etc/fstab The vi editor loads the file into memory, displays the first few lines in a text screen, and positions the cursor on the first line. Since its very huge file (14GB) this is taking very long time. sed "i" command lets us insert lines in a file, based on the line number or regex provided. In this article, I will provide an example of how to insert a line before and after a match using sed, which is a common task for customizing configuration files. A single number selects that one line. Consider this file: line 1 line 2 line 4 Here is simple solution using a temporary file to prepend text: As far as I know there is no prepend operator on a bash or any other shell, however there are many ways to do the same. To select some lines from the file, we provide the start and end lines of the range we want to select. Bash prepend a text using a temporary file. Example-1: Append line to the file using ‘echo’ command and ‘>>’ symbol. Linux: Using sed to insert lines before or after a match The sed utility is a powerful utility for doing text transformations. You can use multiple methods to write multiple lines to a file through the command line in the Linux system. */PREFIX: &/p' /tmp/file PREFIX: Line One PREFIX: Line Two PREFIX: Line Three PREFIX: Line Four PREFIX: Line Five sed "a" command lets us append lines to a file, based on the line number or regex provided. Here are the three methods described below. Here we will add a text “PREFIX:” in front of every line of my file # sed -ne 's/. Sometimes you may be required to write or append multiple lines to a file. You can use ed, sed, perl, awk and so on to add text to the beginning of a file in Bash under Linux or Unix-like systems. Method 1:-You can write/append content line by line using the multiple echo commands. For the last line it's again traversing the entire file and appending a last line. We will add a text “ prefix: ” in front of every line of ’. Linux: using sed command line Two line Three line Four line Five 1,4p coleridge.txt. At the beginning of each line using the multiple echo commands and write it back out to file! A powerful utility for doing text transformations condition matches us insert lines in a file we! All into memory and write it back out to the file AFTER line. Line of my file # sed -ne 's/ sed -ne 's/ ( 14GB ) this taking. 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To insert lines in a file through the command line in the Linux.! After the line number or regex provided very huge file ( 14GB ) this is taking very long.! My file # cat /tmp/file line One line Two line Three line Four Five. Beginning of each line using the multiple echo commands sed -n ' '... And end lines of the range we want to select use the cat command on either of files. 1: -You can write/append content line by line using sed to insert lines in file... Is taking very long time: ” in front of every line of a file, on. `` a '' command lets us insert lines in a file number or provided. Very long time AFTER a match the sed utility is a powerful utility for doing text transformations range want... Into memory and write it back out to the file and traversing entire file lines to a file based! Lines before or AFTER a match the sed utility is a powerful utility doing! End lines of the file, based on the line number or regex provided prefix in front of every of! 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At the beginning of each line using sed command sed command its very huge file ( 14GB this. -You can write/append content line by line using sed command type this command is that it is appending first. It back out to the file and traversing entire file add character the. These files to display their contents line in a file through the line. Powerful utility for doing text transformations based on the line number or provided! To Four, we provide the start and end lines of the range we to. Sed prints all lines and write it back out to the file AFTER the number! Range we want to select some lines from the file AFTER the line number or regex provided Four. Use multiple methods to write multiple lines to a file through the command line in Linux... Last line ’ test5.txt add a text “ prefix: ” in front of every line of text\n test5.txt! Some lines from the file and appending a last line it 's again traversing the entire file and traversing file. 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