grep and find

grep

grep finds and prints lines in files that match a regular expression. In the following example, we search for the string Python:

!grep Python ../index.rst

IPython
`IPython <https://ipython.org/>`_, or *Interactive Python*, was initially an
advanced Python interpreter that has now grown into an extensive project
Today, IPython is not only an interactive interface to Python, but also offers a
number of useful syntactic additions for the language. In addition, IPython is
    * `Miki Tebeka - IPython: The Productivity Booster

The option -w limits the matches to the word boundaries so that IPython is ignored:

!grep  -w Python ../index.rst

`IPython <https://ipython.org/>`_, or *Interactive Python*, was initially an
advanced Python interpreter that has now grown into an extensive project
Today, IPython is not only an interactive interface to Python, but also offers a

-n shows the line numbers that match:

!grep  -n -w Python ../index.rst

8:`IPython <https://ipython.org/>`_, or *Interactive Python*, was initially an
9:advanced Python interpreter that has now grown into an extensive project
11:Today, IPython is not only an interactive interface to Python, but also offers a

-v inverts our search

!grep  -n -v "^ " ../index.rst

1:.. SPDX-FileCopyrightText: 2020 cusy GmbH
2:..
3:.. SPDX-License-Identifier: BSD-3-Clause
4:
5:IPython
6:=======
7:
8:`IPython <https://ipython.org/>`_, or *Interactive Python*, was initially an
9:advanced Python interpreter that has now grown into an extensive project
10:designed to provide tools for the entire life cycle of research computing.
11:Today, IPython is not only an interactive interface to Python, but also offers a
12:number of useful syntactic additions for the language. In addition, IPython is
13:closely related to the `Jupyter project <https://jupyter.org/>`_.
14:
15:.. seealso::
18:
19:.. toctree::
23:

grep has lots of other options. To find out what they are, you can type:

!grep --help

usage: grep [-abcdDEFGHhIiJLlMmnOopqRSsUVvwXxZz] [-A num] [-B num] [-C[num]]
        [-e pattern] [-f file] [--binary-files=value] [--color=when]
        [--context[=num]] [--directories=action] [--label] [--line-buffered]
        [--null] [pattern] [file ...]

In the following example we use the -E option and put the pattern in quotes to prevent the shell from trying to interpret it. The ^ in the pattern anchors the match to the start of the line and the . matches a single character.

!grep -n -E "^.Python" ../index.rst

5:IPython

find

find . searches in this directory whereby the search is restricted to directories with -type d.

!find .. -type d

..
../mypackage
../unix-shell
../unix-shell/.ipynb_checkpoints

With -type f the search is restricted to files.

!find . -type f

./index.rst
./shell-variables.ipynb.license
./sorted-length.txt
./create-delete.ipynb
./grep-find.ipynb.license
./create-delete.ipynb.license
./length.txt
./file-system.ipynb
./pipes-filters.ipynb
./shell-variables.ipynb
./pipes-filters.ipynb.license
./file-system.ipynb.license
./grep-find.ipynb

With -mtime the search is limited to the last X days, in our example to the last day:

!find . -mtime -1

.
./sorted-length.txt
./create-delete.ipynb
./length.txt
./file-system.ipynb
./pipes-filters.ipynb
./.ipynb_checkpoints
./grep-find.ipynb

With -name you can filter the search by name.

!find .. -name "*.rst"

../index.rst
../unix-shell/index.rst
../extensions.rst
../start.rst

Now we count the characters in the files with the suffix .rst:

!wc -c $(find .. -name "*.rst")

     923 ../index.rst
     540 ../unix-shell/index.rst
    2229 ../extensions.rst
     820 ../start.rst
    4512 total

It is also possible to search for a regular expression in these files:

!grep "ipython.org" $(find .. -name "*.rst")

../index.rst:`IPython <https://ipython.org/>`_, or *Interactive Python*, was initially an

Finally, we filter out all results whose path contains ipynb_checkpoints:

!find . -name "*.ipynb" | grep -v ipynb_checkpoints

./create-delete.ipynb
./file-system.ipynb
./pipes-filters.ipynb
./shell-variables.ipynb
./grep-find.ipynb