[R] sorting of files using system

[Maria Ninova]

Hello, I came across the following oddity when it comes to file order 
using the system command: different system commands return files in a 
different order:
This is a real filenames example:

 > system("ls gw1kb_tables/rpkm_47*", intern=T)
[1] "gw1kb_tables/rpkm_479_Input.tab"
[2] "gw1kb_tables/rpkm_479_IP.tab"

 > system("for file in gw1kb_tables/rpkm_4*; do echo $file;done" )
gw1kb_tables/rpkm_479_IP.tab
gw1kb_tables/rpkm_479_Input.tab

As you see, in the first case, the "Input" comes first, while in the 
second, the IP comes first; I was surprised by this result and not sure 
if it's expected?
I am using R version 3.2.2 (2015-08-14) on Ubuntu 15.04

Thank you in advance,

Maria