How do I remove a specific line from a file in Unix?

To Remove the lines from the source file itself, use the -i option with sed command. If you dont wish to delete the lines from the original source file you can redirect the output of the sed command to another file.

How do I remove a specific line from a file?

You can use the “stream editor for filtering and transforming text” sed. Here, -i means edit the file inplace. d is the command to “delete the pattern space; immediately start next cycle”.

How do I cut a specific line in Linux?

The cut command in UNIX is a command for cutting out the sections from each line of files and writing the result to standard output. It can be used to cut parts of a line by byte position, character and field. Basically the cut command slices a line and extracts the text.

How do I remove a line from a string in Unix?

In the following example, we will use the action option of the sed command to delete lines containing the specified string in the text file. As follows, we delete the line that contains the string “sed” in the file. You can also use the sed -i ‘/sed/d’ text. txt to modify the contents of the file directly.

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How do you remove the last line of a file in Unix?

6 Answers

  1. Use sed -i ‘$d’ <file> to edit file in place. – …
  2. What would be for deleting the last n lines, where n is any integer number? – …
  3. @JoshuaSalazar for i in {1..N}; do sed -i ‘$d’ <file>; done dont forget to replace N – ghilesZ Oct 21 ’20 at 13:23.

How do I change a delimiter in Unix?

Shell script to change the delimiter of a file:

Using the shell substitution command, all the commas are replaced with the colons. ‘${line/,/:}’ will replace only the 1st match. The extra slash in ‘${line//,/:}’ will replace all the matches. Note: This method will work in bash and ksh93 or higher, not in all flavors.

What is the use of awk in Linux?

Awk is a utility that enables a programmer to write tiny but effective programs in the form of statements that define text patterns that are to be searched for in each line of a document and the action that is to be taken when a match is found within a line. Awk is mostly used for pattern scanning and processing.

How do you cut a file in Linux?

Each line of the file can be sliced and the required data can be retrieved easily by using `cut` command. It can also be used to cut text by delimiter or character or byte position.

Linux cut command examples.

Option tag Description
–output-delimiter=STRING Use STRING value as output delimiter.
-z or –zero-terminated Use NULL as line delimiter.

How do I remove the last 10 lines in Unix?

It’s a little roundabout, but I think it’s easy to follow.

  1. Count up the number of lines in the main file.
  2. Subtract the number of lines you want to remove from the count.
  3. Print out the number of lines you want to keep and store in a temp file.
  4. Replace the main file with the temp file.
  5. Remove the temp file.
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How do I remove the first line in Unix?

To delete a particular line in file:

  1. Delete first line sed ‘1d’ file.
  2. Delete first and third line sed ‘1d3d’ file.

What is D in sed?

sed. From the sed documentation: d Delete the pattern space; immediately start next cycle.

How do you delete the first 1000 lines in a file Unix?

Remove first N lines of a file in place in unix command line

  1. Both sed -i and gawk v4.1 -i -inplace options are basically creating temp file behind the scenes. IMO sed should be the faster than tail and awk . – …
  2. tail is multiple times faster for this task, than sed or awk . (

What is NR in awk command?

NR is a AWK built-in variable and it denotes number of records being processed. Usage : NR can be used in action block represents number of line being processed and if it is used in END it can print number of lines totally processed. Example : Using NR to print line number in a file using AWK.

How do I print the last 10 lines of a file in Linux?

Linux tail command syntax

Tail is a command which prints the last few number of lines (10 lines by default) of a certain file, then terminates. Example 1: By default “tail” prints the last 10 lines of a file, then exits. as you can see, this prints the last 10 lines of /var/log/messages.

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