Tree command in Linux with examples

In UNIX/LINUX systems, as well as MS-DOS and Microsoft Windows, tree is a recursive directory listing program that produces a depth-indented listing of files. With no arguments, tree lists the files in the current directory. When directory arguments are given, tree lists all the files or directories found in the given directories each in turn. Upon completion of listing all files and directories found, tree returns the total number of files and directories listed. There are options to change the characters used in the output, and to use color output. 

Syntax :

$ tree [-adfgilnopqrstuxACDFNS] [-L level [-R]] [-H baseHREF] [-T title] [-o filename] 
[–nolinks] [-P pattern] [-I pattern] [–inodes] [–device] [–noreport] [–dirsfirst] 
[–version] [–help] [directory …] 

Options :
–help : Outputs a verbose usage listing. 
–version : Outputs the version of tree. 
-a : All files are printed. By default, tree does not print hidden files (those beginning with a dot `.’). In no event does tree print the file system constructs `.’ (current directory) and `..’ (previous directory). 
-d : List directories only. 
-f : Prints the full path prefix for each file. 
-i : Tree will not print the indentation lines. Useful when used in conjunction with the -f option. 
-l : Follows symbolic links to directories as if they were directories. Links that would result in a recursive loop are avoided. 
-x : Stay on the current file system only, as with find -xdev. 
-P pattern : List only those files that match the wild-card pattern. 
Note : you must use the -a option to also consider those files beginning with a dot `.’ for matching. Valid wildcard operators are `*’ (any zero or more characters), `?’ (any single character), `[…]’ (any single character listed between brackets (optional – (dash) for character range may be used: ex: [A-Z]), and `[^…]’ (any single character not listed in brackets) and `|’ separates alternate patterns. 
-I pattern : Do not list those files that match the wild-card pattern. 
–prune : Makes tree prune empty directories from the output, useful when used in conjunction with -P or -I. 
–filelimit # : Do not descend directories that contain more than # entries. 
–timefmt format : Prints (implies -D) and formats the date according to the format string which uses the strftime syntax. 
–noreport : Omits printing of the file and directory report at the end of the tree listing. 
-p : Print the protections for each file (as per ls -l). 
-s : Print the size of each file along with the name. 
-u : Print the username, or UID # if no username is available, of the file. 
-g : Print the group name, or GID # if no group name is available, of the file. 
-D : Print the date of the last modification time for the file listed. 
–inodes : Prints the inode number of the file or directory 
–device : Prints the device number to which the file or directory belongs 
-F : Append a `/’ for directories, a `=’ for socket files, a `*’ for executable files and a `|’ for FIFO’s, as per ls -F 
-q : Print non-printable characters in file names as question marks instead of the default carrot notation. 
-N : Print non-printable characters as is instead of the default carrot notation. 
-r : Sort the output in reverse alphabetic order. 
-t : Sort the output by last modification time instead of alphabetically. 
–dirsfirst : List directories before files. 
-n : Turn colorization off always, over-ridden by the -C option. 
-C : Turn colorization on always, using built-in color defaults if the LS_COLORS environment variable is not set. Useful to colorize output to a pipe. 
-A : Turn on ANSI line graphics hack when printing the indentation lines. 
-S : Turn on ASCII line graphics (useful when using linux console mode fonts). This option is now equivalent to `–charset=IBM437′ and will eventually be depreciated. 
-L level : Max display depth of the directory tree. 
-R : Recursively cross down the tree each level directories (see -L option), and at each of them execute tree again adding `-o 00Tree.html’ as a new option. 
-H baseHREF : Turn on HTML output, including HTTP references. Useful for ftp sites. baseHREF gives the base ftp location when using HTML output. That is, the local directory may be `/local/ftp/pub’, but it must be referenced as `ftp://host-name.organization.domain/pub’ (baseHREF should be `ftp://hostname.organization.domain’). Hint: don’t use ANSI lines with this option, and don’t give more than one directory in the directory list. If you want to use colors via CSS stylesheet, use the -C option in addition to this option to force color output. 
-T title : Sets the title and H1 header string in HTML output mode. 
–charset charset : Set the character set to use when outputting HTML and for line drawing. 
–nolinks : Turns off hyperlinks in HTML output. 
-o file name : Send output to file name. 

Examples : 

1. How to install tree in Unix/Linux. 
By default the tree command is not installed. Type the following command to install the same on a RHEL / CentOS / Fedora Linux using yum command : 

 # yum install tree 

If you are using Debian / Mint / Ubuntu Linux, type the following apt-get command to install the tree command : 

 $ sudo apt install tree 

If you are using Apple OS X, type:  

brew install tree

2. Display the tree hierarchy of a directory  

 $ tree -a ./GFG 

Output :  

3. List files with entered pattern  

 $ tree -P sample* . 

Output :  

4. List those directories which have greater ‘N’ number of files/directories  

 $ tree --filelimit 3 ./GFG 
 

5. List files with their permissions.  

 $ tree -p ./GFG 

Output :  

6. Prints the device number to which the file or directory belongs.  

 $ tree --device ./GFG 

Output :  

7. Prints the output by last modification time instead of alphabetically.  

 $ tree -t ./GFG 

Output :  

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