Ubuntu – grep -r “pattern” not responding

command linegrep

grep version is 2.10, and it does not respond anything, even on a small set of small files, while the same line on another Ubuntu machine works fine where grep version is 2.16…

The command is:

grep -r "myVariable"

Instead of returning nothing, or some file names and lines, like this:

path/to/file.c:     myVariable++;
path/to/file2.c:    int myVariable;

The command shell stays busy and I have to halt it using ctrl+C

What is the problem or how do I investigate it?

Best Answer

Since you don't specify any input file, grep waits for you to provide input data on its standard input.

The behavior where -r will use the current directory by default is non-standard (in fact, -r itself is), and was introduced in GNU grep 2.11.

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Ubuntu – Count pattern instances using grep

Your command would actually count the number of lines containing / in the standard output of command /home/usr/bin/test

Here are some options to count the instances of / in the string /home/usr/bin/test:

grep -o '/' <<< "/home/usr/bin/test" | wc -l

tr -dc '/' <<< "/home/usr/bin/test" | wc -c

Ubuntu – grep pattern with leading spaces

Your line 2 and 3 has upper case P and requires zero or more spaces, so specify exactly that:

$ grep '[[:blank:]]*Pattern'  input.txt                                  
 Pattern to be recognized
         Pattern to be recognized here also

Personally, I'd recommend extending your pattern with something else, like '[[:blank:]]Pattern.*recognized'

Best Answer

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