commands

All posts tagged commands

(Copied all these from https://www.binarytides.com/linux-find-command-examples/)

1. List all files in current and subdirectories

This command lists out all the files in the current directory as well as the subdirectories in the current directory.

The command is same as the following

2. Search specific directory or path

The following command will look for files in the test directory in the current directory. Lists out all files by default.

The following command searches for files by their name.

We can also use wildcards

Note that all subdirectories are searched recursively. So this is a very powerful way to find all files of a given extension.

Trying to search the “/” directory which is the root, would search the entire file system including mounted devices and network storage devices. So be careful. Of course, you can press Ctrl + c anytime to stop the command.

Ignore the case

It is often useful to ignore the case when searching for file names. To ignore the case, just use the “iname” option instead of the “name” option.

3. Limit depth of directory traversal

The find command by default travels down the entire directory tree recursively, which is time and resource consuming. However, the depth of directory traversal can be specified. For example, we don’t want to go more than 2 or 3 levels down in the subdirectories. This is done using the maxdepth option.

The second example uses maxdepth of 1, which means it will not go lower than 1 level deep, either only in the current directory.

This is very useful when we want to do a limited search only in the current directory or max 1 level deep subdirectories and not the entire directory tree which would take more time.

Just like maxdepth there is an option called mindepth which does what the name suggests, that is, it will go at least N level deep before searching for the files.

4. Invert match

It is also possible to search for files that do no match a given name or pattern. This is helpful when we know which files to exclude from the search.

So in the above example, we found all files that do not have the extension of php, either non-php files. The find command also supports the exclamation mark inplace of not.

5. Combine multiple search criteria

It is possible to use multiple criteria when specifying name and inverting. For example

The above find command looks for files that begin with abc in their names and do not have a php extension. This is an example of how powerful search expressions can be built with the find command.

OR operator

When using multiple name criteria, the find command would combine them with AND operator, which means that only those files which satisfy all criteria will be matched. However, if we need to perform an OR based matching then the find command has the “o” switch.

The above command search for files ending in either the php extension or the txt extension.

6. Search only files or only directories

Sometimes we want to find only files or only directories with a given name. Find can do this easily as well.

Quite useful and handy!

7. Search multiple directories together

So let’s say you want to search inside 2 separate directories. Again, the command is very simple

Check, that it listed files from 2 separate directories.

8. Find hidden files

Hidden files on Linux begin with a period. So its easy to mention that in the name criteria and list all hidden files.

9. Find files with certain permissions

The find command can be used to find files with a specific permission using the “perm” option. The following command searches for files with the permission 0664

This can be useful to find files with wrong permissions which can lead to security issues. Inversion can also be applied to permission checking.

10. Find files with sgid/suid bits set

The “perm” option of find command accepts the same mode string like chmod. The following command finds all files with permission 644 and sgid bit set.

Similarly, use 1664 for sticky bit. The perm option also supports using an alternative syntax instead of octal numbers.

Note that the “2>/dev/null” removes those entries that have an error of “Permission Denied”

11. Find readonly files

Find all Read Only files.

12. Find executable files

The following command will find executable files

13. Find files owned by particular user

To find all or single file called tecmint.txt under /root directory of owner root.

We could also specify the name of the file or any name related criteria along with user criteria

It’s very easy to see, how we can build up criteria after criteria to narrow down our search for matching files.

14. Search files belonging to group

Find all files that belong to a particular group.

Did you know you could search your home directory by using the ~ symbol?

Easy!!

Search file and directories based on modification date and time

Another great search criteria that the find command supports is a modification and accessed date/times. This is very handy when we want to find out which files were modified as a certain time or date range. Let’s take a few examples

15. Find files modified N days back

To find all the files which are modified 50 days back.

16. Find files accessed in last N days

Find all files that were accessed in the last 50 days.

17. Find files modified in a range of days

Find all files that were modified between 50 to 100 days ago.

18. Find files changed in last N minutes.

Find files modified within the last 1 hour.

19. Files modified in last hour

To find all the files which are modified in last 1 hour.

20. Find Accessed Files in Last 1 Hour

To find all the files which are accessed in last 1 hour.

21. Find files of given size

Search files and directories based on size. To find all 50MB files, use.

22. Find files in a size range

To find all the files which are greater than 50MB and less than 100MB.

23. Find largest and smallest files

The find command, when used in combination with the ls and sort command, can be used to list out the largest files.
The following command will display the 5 largest file in the current directory and its subdirectory. This may take a while to execute depending on the total number of files the command has to process.

Similarly when sorted in ascending order, it would show the smallest files first

24. Find empty files and directories

The following command uses the “empty” option of the find command, which finds all files that are empty.

To file all empty directories use the type “d”.

Really very simple and easy

Some advanced operations

The find command not only finds files based on certain criteria, it can also act upon those files using any Linux command. For example, we might want to delete some files.

Here are some quick examples

25. List out the found files

Let’s say we found files using find command, and now want to list them out as the ls command would have done. This is very easy.

26. Delete all matching files or directories

The following command will remove all text files in the tmp directory.

The same operating can be carried out with directories, just put type d, instead of type f.

Let’s take another example where we want to delete files larger than 100MB

Wanted to translate two-digit years into 4 digit years for the 1900s only.

Two digits were getting written as 35-37 or 40-50 in the spreadsheet.  This needed to be translated to 1935 1936 1937 or 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950.

Or

By creating a file named ‘years’ with two-digit years on each line.

67 80

55 60

45 50

 

Wanted to have Excel do this automatically.  But for now, I’m just using this method and copy/pasting results into the spreadsheet.   If anyone has any suggestions, please let me know.