Linux: Find a List of Files in a Dictionary Recursively

Linux: Find a List of Files in a Dictionary recursively

The easiest way may be the following:

cat orig_filenames.txt | while read file ; do find /dest/directory -name "$file" ; done > output_file_with_paths 

Recursively counting files in a Linux directory

This should work:

find DIR_NAME -type f | wc -l

Explanation:

• -type f to include only files.
• | (and not ¦) redirects find command's standard output to wc command's standard input.
• wc (short for word count) counts newlines, words and bytes on its input (docs).
• -l to count just newlines.

Notes:

• Replace DIR_NAME with . to execute the command in the current folder.
• You can also remove the -type f to include directories (and symlinks) in the count.
• It's possible this command will overcount if filenames can contain newline characters.

Explanation of why your example does not work:

In the command you showed, you do not use the "Pipe" (|) to kind-of connect two commands, but the broken bar (¦) which the shell does not recognize as a command or something similar. That's why you get that error message.

Linux find file names with given string recursively

Use the find command,

find . -type f -name "*John*"

Finding a key recursively in a dictionary

when you recurse, you need to return the result of _finditem

def _finditem(obj, key):
    if key in obj: return obj[key]
    for k, v in obj.items():
        if isinstance(v,dict):
            return _finditem(v, key)  #added return statement

To fix the actual algorithm, you need to realize that _finditem returns None if it didn't find anything, so you need to check that explicitly to prevent an early return:

def _finditem(obj, key):
    if key in obj: return obj[key]
    for k, v in obj.items():
        if isinstance(v,dict):
            item = _finditem(v, key)
            if item is not None:
                return item

Of course, that will fail if you have None values in any of your dictionaries. In that case, you could set up a sentinel object() for this function and return that in the case that you don't find anything -- Then you can check against the sentinel to know if you found something or not.

How to loop through a directory recursively to delete files with certain extensions

find is just made for that.

find /tmp -name '*.pdf' -or -name '*.doc' | xargs rm

Getting a list of all subdirectories in the current directory

Do you mean immediate subdirectories, or every directory right down the tree?

Either way, you could use os.walk to do this:

os.walk(directory)

will yield a tuple for each subdirectory. Ths first entry in the 3-tuple is a directory name, so

[x[0] for x in os.walk(directory)]

should give you all of the subdirectories, recursively.

Note that the second entry in the tuple is the list of child directories of the entry in the first position, so you could use this instead, but it's not likely to save you much.

However, you could use it just to give you the immediate child directories:

next(os.walk('.'))[1]

Or see the other solutions already posted, using os.listdir and os.path.isdir, including those at "How to get all of the immediate subdirectories in Python".

How can I use grep to find a word inside a folder?

grep -nr 'yourString*' .

The dot at the end searches the current directory. Meaning for each parameter:

-n            Show relative line number in the file
'yourString*' String for search, followed by a wildcard character
-r            Recursively search subdirectories listed
.             Directory for search (current directory)

grep -nr 'MobileAppSer*' . (Would find MobileAppServlet.java or MobileAppServlet.class or MobileAppServlet.txt; 'MobileAppASer*.*' is another way to do the same thing.)

To check more parameters use man grep command.

How can I get the list of files in a directory using C or C++?

UPDATE 2017:

In C++17 there is now an official way to list files of your file system: std::filesystem. There is an excellent answer from Shreevardhan below with this source code:

#include <string>
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;

int main()
{
    std::string path = "/path/to/directory";
    for (const auto & entry : fs::directory_iterator(path))
        std::cout << entry.path() << std::endl;
}

Old Answer:

In small and simple tasks I do not use boost, I use dirent.h. It is available as a standard header in UNIX, and also available for Windows via a compatibility layer created by Toni Ronkko.

DIR *dir;
struct dirent *ent;
if ((dir = opendir ("c:\\src\\")) != NULL) {
  /* print all the files and directories within directory */
  while ((ent = readdir (dir)) != NULL) {
    printf ("%s\n", ent->d_name);
  }
  closedir (dir);
} else {
  /* could not open directory */
  perror ("");
  return EXIT_FAILURE;
}

It is just a small header file and does most of the simple stuff you need without using a big template-based approach like boost (no offence, I like boost!).

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