How to redirect grep to an output file?

How to redirect grep to an output file?

grep -n “test” * | grep -v “mytest” > output-file will match all the lines that have the string “test” except the lines that match the string “mytest” (that’s the switch -v) – and will redirect the result to an output file. Redirection of program output is performed by the shell.

Is there a switch for the grep command?

Also is there a switch for the Grep command that provides cleaner results for better readability, such as a line feed between each entry or a way to justify file names and search results? For instance, a away to change… The -n will print the line number and the > will redirect grep-results to the output-file.

How to capture the output of grep into a variable?

If I understand it correct, you want to capture the output of grep into a variable and append any error to the logfile. The $ (…) syntax denotes command substitution, i.e. outputs the result of the command into a variable. By default it would capture the STDOUT of the command into the variable and the STDERR is printed to the console.

How to redirect a command to a file?

By default it would capture the STDOUT of the command into the variable and the STDERR is printed to the console. In order to redirect the STDERR to a file, you would need to perform the redirection within the command itself, i.e. within $ (…).

Why does grep not work in Ubuntu 11.10?

On Ubuntu 11.10 does not produce any output. I believe the reason for this is that grep is buffering its output. To tell GNU grep to spit out output line-by-line, use the –line-buffered option: See also this SO question for other potential solutions.

Which is the correct way to grep and replace?

This will revert your replaced strings, so you will be back to the beginning of the problem. The correct way to search for a string and replace it is to skip find and use grep instead in order to ignore the binary files:

How to remove blank lines in grep Stack Overflow?

For instance your regular expression matches the beginning of the string then one or more spaces using the POSIX standard then the end of the string, i.e. with grep -v it removes all lines that are only spaces.

How to grep text from string to string?

Supposing “the text I need” is just one line, you should check that both string1 and string2 appear (Alex’s solution only checks one thing). if you know that “the text i need” is always above or always below string 1 or string 2, you can use grep -A 1 “string 1” $file | tail -1 or grep -B 1 “string 2” $file | head -1

Is there a way to format a file with grep?

While grep can format the output on the screen, this command is unable to modify a file in place. To do this, we’d need a file editor like ed. In the next article, we’ll use sed to achieve the same thing we did here with grep. While we’re still on grep, let’s examine the /etc/sudoers file.

How to count the number of lines in a file with grep?

Let’s see if grep offers an option to count lines in a given file. Ironically, we’ll use grep to grep for the option as follows: So, we obviously need -c, or the long option –count, to count the number of lines in a given file. Counting the lines in /usr/share/dict/words yields: