Search and replace text in a file unix

This is useful to protect against file names starting with -. If a file is of a certain type, for example, executable see man find for more options :. Replace foo with bar only if there is a baz later on the same line:. There are many variations of this theme, to learn more about such regular expressions, see here.

Replace foo with bar only if foo is found on the 3d column field of the input file assuming whitespace-separated fields :. For a different field separator : in this example use:. NOTE: both the awk and perl solutions will affect spacing in the file remove the leading and trailing blanks, and convert sequences of blanks to one space character in those lines that match.

If you have a large number of patterns, it is easier to save your patterns and their replacements in a sed script file:. That will be quite slow for long lists of patterns and large data files so you might want to read the patterns and create a sed script from them instead. The method is very general though: basically, if you can create an output stream which looks like a sed script, then you can source that stream as a sed script by specifying sed 's script file as - stdin.

When working with fixed-strings as patterns, it is good practice to escape regular expression metacharacters. You can do this rather easily:. A good r e pl acement Linux tool is rpl , that was originally written for the Debian project, so it is available with apt-get install rpl in any Debian derived distro, and may be for others, but otherwise you can download the tar. Note that if the string contains spaces it should be enclosed in quotation marks.

By default rpl takes care of capital letters but not of complete words , but you can change these defaults with options -i ignore case and -w whole words. You can also specify multiple files :. Or even specify the extensions -x to search or even search recursively -R in the directory:. Finally, if you are unsure what exactly will happen, use the -s simulate mode. How to do a search and replace over multiple files suggests:. Update: The above result will fail on filenames that contain whitespaces.

Instead, use:. For example,. A nice feature is that qsubst will do a query-replace , i. How to get it: qsubst was invented by der Mouse from McGill and posted to comp. Updated versions exist. For example, the NetBSD version qsubst. See Rust regex documentation for regular expression syntax and features. Like grep , the -F option will allow fixed strings to be matched, a handy option which I feel sed should implement too.

I needed something that would provide a dry-run option and would work recursively with a glob, and after trying to do it with awk and sed I gave up and instead did it in python. The script searches recursively all files matching a glob pattern e.

Every long option such as --search-regex has a corresponding short option, i. Run with -h to see all options. Here is an updated version of the script which highlights the search terms and replacements with different colors. Here I use grep to tell if it is going to change a file so I can count the number of lines changed, and replacements made, to output at the end , then I use sed to actually change the file.

Notice the single line of sed usage at the very end of the Bash function below:. Replace do with bo so that "doing" becomes "boing" I know, we should be fixing spelling errors not creating them : :. I just wrote a wrapper around RipGrep to give it this feature. I call it rgr for RipGrep Replace, since it will do the find-and-replace feature on your disk.

Sign up to join this community. In the current snippet I'm using it to replace text with the following parameters:. The s stands for substitute i. How do you replace a character in Linux? Change characters. The tr command in Linux is used to change characters. To change every occurence of the letter a in the file into the uppercase A , we can use the following command: We can specify more than one character to change:.

How do you use Xargs? While echo is the default command xargs executes, you can explicitly specify any other command. For example, you can pass the find command along with its '-name' option as an argument to xargs , and then pass the name of the file or type of files you want to find to search as input through stdin.

How do you replace a word in vi? Advanced Search and Replace. How do you grep? How to Use the Grep Command. You may also redirect output from a command to grep using a pipe: Regex patterns are also supported by the -E option if you want to search for a set of strings rather than one literal:. How do I grep in a directory and subdirectory? To Search Subdirectories. How do I find and replace text in a file in Python? Python to search text file string and replace it.

Does SED use regex? Well, a regular expression , or regex , in general, is a pattern of text you define that a Linux program like sed or awk uses to filter text. We saw some of those patterns when introducing basic Linux commands and saw how the ls command uses wildcard characters to filter output.

I have two files a. Dear All, I do not have any knowledge of scripting. I want to replace specific lines of a text file with a specific text. Like I have one file which is "original file" and one file "changes file" which has list of lines which I want to replace in original file with a specific string. I want the I need to find particular string in file1 text file and replace it with a value from another text file file2 the file2 has only one line and the value to be replaced with is in the second column.

Find text containing paths and replace with a string in all the python files. I need to replace a specific path occurrence with a variable name. Find and replace string from file which contains variable and path - SH. I think you should play a bit with sharps and sed:b: 2 Replies.

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