linux command to get size of files and directories present in a particular folder?

Go to the chosen directory and execute:

$ du -d 1 -h

where:

-d 1 is the depth of the directories

-h is the human-readable option

You'll see like that:

0   ./proc
8.5M    ./run
0   ./sys
56M ./etc
12G ./root
33G ./var
23M ./tmp
3.2G    ./usr
154M    ./boot
26G ./home
0   ./media
0   ./mnt
421M    ./opt
0   ./srv
2.6G    ./backups
80G .

All you need is -l and --block-size flags

Size of all files and directories under working directory (in MBs)

ls -l --block-size=M

Size of all files and directories under working directory (in GBs)

ls -l --block-size=G

Size of a specific file or directory

ls -l --block-size=M my_file.txt
ls -l --block-size=M my_dir/

ls --help

-l use a long listing format

--block-size=SIZE: scale sizes by SIZE before printing them; e.g., '--block-size=M' prints sizes in units of 1,048,576 bytes; see SIZE format below

SIZE is an integer and optional unit (example: 10M is 10*1024*1024). Units are K, M, G, T, P, E, Z, Y (powers of 1024) or KB, MB, ... (powers of 1000).

If you are using it in a script, use stat.

$ date | tee /tmp/foo
Wed Mar 13 05:36:31 UTC 2019

$ stat -c %s /tmp/foo
29

$ ls -l /tmp/foo
-rw-r--r--  1 bruno  wheel  29 Mar 13 05:36 /tmp/foo

That will give you size in bytes. See man stat for more output format options.

The OSX/BSD equivalent is:

$ date | tee /tmp/foo
Wed Mar 13 00:54:16 EDT 2019

$ stat -f %z /tmp/foo
29

$ ls -l /tmp/foo
-rw-r--r--  1 bruno  wheel  29 Mar 13 00:54 /tmp/foo

To get the total size of directory or the total size of file use,

du -csh <directory or filename*> | grep total

Use ls command with -h argument: [root@hots19 etc]# ls -lh
h : for human readable.

Exemple: 
    [root@CIEYY1Z3 etc]# ls -lh
    total 1.4M
    -rw-r--r--.  1 root   root      44M Sep 15  2015 adjtime
    -rw-r--r--.  1 root   root     1.5K Jun  7  2013 aliases
    -rw-r--r--   1 root   root      12K Nov 25  2015 aliases.db
    drwxr-xr-x.  2 root   root     4.0K Jan 11  2018 alternatives
    -rw-------.  1 root   root      541 Jul  8  2014 anacrontab
    -rw-r--r--.  1 root   root      55M Sep 16  2014 asound.conf
    -rw-r--r--.  1 root   root       1G Oct  6  2014 at.deny

You can use ncdu disk usage analyzer here. It displays the size of the files and directories in an ncurses interface. You can navigate to each directory and see the files sizes from the same interface.

To install

$ sudo apt-get install ncdu

To analyze

$ ncdu <directory>

du -sh [file_name]

works perfectly to get size of a particular file.

I'm a Ubuntu 16.04 user myself and I find that the ll command is by far the easiest way to see a directory's contents. I've noticed that not all Linux distributions support this command, but there's probably a workaround/install for each distro out there.

Example:

user@user-XPS-15-9560:/$ ll
total 188
drwxr-xr-x  27 root root  4096 Jan 26 09:13 ./
drwxr-xr-x  27 root root  4096 Jan 26 09:13 ../
drwxr-xr-x   2 root root  4096 Jan 22 15:13 bin/
drwxr-xr-x   4 root root 12288 Jan 29 11:35 boot/
drwxr-xr-x   2 root root  4096 Sep  3 18:14 cdrom/
drwxr-xr-x  20 root root  4440 Feb  5 08:43 dev/
drwxr-xr-x 153 root root 12288 Feb  2 15:17 etc/
drwxr-xr-x   4 root root  4096 Sep  3 18:15 home/
...

The biggest advantage for me is that it's quick and really intuitive to use.

UPDATE: what I didn't know was that on Ubuntu it's a pre-configured alias. You can easily set it yourself by executing alias ll="ls -la" on the command line, or by adding this entry in your .bashrc config file:

sudo nano ~/.bashrc
...add line described above and save file by pressing Ctrl+X and Y...
source ~/.bashrc

ls -sh video.mp4 | sed s/video.mp4//g

output, 5.6M

I prefer this command ll -sha.

You have to differenciate between file size and disk usage. The main difference between the two comes from the fact that files are "cut into pieces" and stored in blocks.

Modern block size is 4KiB, so files will use disk space multiple of 4KiB, regardless of how small they are.

If you use the command stat you can see both figures side by side.

stat file.c

If you want a more compact view for a directory, you can use ls -ls, which will give you usage in 1KiB units.

ls -ls dir

Also du will give you real disk usage, in 1KiB units, or dutree with the -u flag.

Example: usage of a 1 byte file

$ echo "" > file.c

$ ls -l file.c
-rw-r--r-- 1 nacho nacho 1 Apr 30 20:42 file.c

$ ls -ls file.c
4 -rw-r--r-- 1 nacho nacho 1 Apr 30 20:42 file.c

$ du file.c
4 file.c

$ dutree file.c
[ file.c 1 B ]

$ dutree -u file.c
[ file.c 4.00 KiB ]

$ stat file.c
 File: file.c
 Size: 1 Blocks: 8 IO Block: 4096 regular file
Device: 2fh/47d Inode: 2185244 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1000/ nacho) Gid: ( 1000/ nacho)
Access: 2018-04-30 20:41:58.002124411 +0200
Modify: 2018-04-30 20:42:24.835458383 +0200
Change: 2018-04-30 20:42:24.835458383 +0200
 Birth: -

In addition, in modern filesystems we can have snapshots, sparse files (files with holes in them) that further complicate the situation.

You can see more details in this article: understanding file size in Linux

go to specific directory then run below command

# du -sh * 

4.0K    1
4.0K    anadb.sh --> Shell file
4.0K    db.sh/    --> shell file
24K     backup4/  --> Directory
8.0K    backup6/  --> Directory 
1.9G    backup.sql.gz  --> sql file