Size() vs ls -la vs du -h which one is correct size?

Question

I was compiling a custom kernel, and I wanted to test the size of the image file. These are the results:

ls -la | grep vmlinux
-rwxr-xr-x   1 root   root   8         


        

Answer 1

Two definition need to be understood

1 runtime vs storetime (this is why size differs)

2 file depth vs directory (this is why du differs)

Look at the below example:

[root@localhost test]# ls -l
total 36
-rw-r--r-- 1 root root   712 May 12 19:50 a.c
-rw-r--r-- 1 root root  3561 May 12 19:42 a.h
-rwxr-xr-x 1 root root 71624 May 12 19:50 a.out
-rw-r--r-- 1 root root  1403 May  8 00:15 b.c
-rw-r--r-- 1 root root  1403 May  8 00:15 c.c
[root@localhost test]# du -abch --max-depth=1
1.4K    ./b.c
1.4K    ./c.c
3.5K    ./a.h
712     ./a.c
70K     ./a.out
81K     .
81K     total
[root@localhost test]# ls -l
total 36
-rw-r--r-- 1 root root   712 May 12 19:50 a.c
-rw-r--r-- 1 root root  3561 May 12 19:42 a.h
-rwxr-xr-x 1 root root 71624 May 12 19:50 a.out
-rw-r--r-- 1 root root  1403 May  8 00:15 b.c
-rw-r--r-- 1 root root  1403 May  8 00:15 c.c
[root@localhost test]# size a.out
   text    data     bss     dec     hex filename
   3655     640      16    4311    10d7 a.out

If using size not on executable, OS will report an error.