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sh is a real file or just a link?

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# 1  
Old 11-09-2010
sh is a real file or just a link?
Hi, I'm confused about sh. someone help me.Thanks!

Question:
1. sh is a real file or just a link to other shells suck as bash ksh, on Unix/Linux such as AIX HP-UX Solaris Redhat? How to find it out?
2. Does sh is the earliest shell on Unix?

Looking for your answer online!
# 2  
Old 11-09-2010
depand on. There are several sh in the system.

For example, in Solaris,

Code:
-bash-3.00$ ls -l /usr/bin/sh
lrwxrwxrwx 1 root root 13 Mar  5  2007 /usr/bin/sh -> ../../sbin/sh  
-bash-3.00$ ls -l /bin/sh
lrwxrwxrwx 1 root root 13 Mar  5  2007 /bin/sh -> ../../sbin/sh

So both /usr/bin/sh and /bin/sh are link, link to /sbin/sh (real sh)
This User Gave Thanks to rdcwayx For This Post:
jackliang
# 3  
Old 11-09-2010
en,thaks.
And the 2nd question:
if we say sh, does that mean the earliest shell on Unix, I mean the real file?
# 4  
Old 11-09-2010
at rhel 5.5 here:
Code:
[root@newinstaller19 ~]# which sh
/bin/sh
[root@newinstaller19 ~]# ls -l /bin/sh
lrwxrwxrwx 1 root root 4 Oct 12 09:28 /bin/sh -> bash
[root@newinstaller19 ~]#

and then:
Code:
[root@newinstaller19 ~]# which bash
/bin/bash
[root@newinstaller19 ~]# ls -l /bin/bash
-rwxr-xr-x 1 root root 801512 Oct 21  2008 /bin/bash
[root@newinstaller19 ~]#

---------- Post updated at 04:56 PM ---------- Previous update was at 04:52 PM ----------

Quote:
Originally Posted by jackliang
en,thaks.
And the 2nd question:
if we say sh, does that mean the earliest shell on Unix, I mean the real file?
why don't you read Unix shell - Wikipedia, the free encyclopedia
This User Gave Thanks to Yogesh Sawant For This Post:
jackliang
# 5  
Old 11-09-2010
AFAIK of the modern OS, only on Solaris /bin/sh points to an actual bare-bones Bourne Shell, which is indeed the "earliest shell".
On most other modern systems /bin/sh is either a soft link or a hard link to a POSIX-compliant shell, which may have additional features.
On Solaris, /usr/xpg4/bin/sh should be used instead.

If you stick to the features listed on this page: POSIX Shell & Utilities your scripts should work across platforms...
Last edited by Scrutinizer; 11-09-2010 at 07:34 AM..
These 2 Users Gave Thanks to Scrutinizer For This Post:
gc_sw jackliang
# 6  
Old 11-09-2010
thanks a lot to all of you guys.
# 7  
Old 11-09-2010
And HP-UX /sbin/sh... the /usr/bin/sh is the posix...
Code:
ran:/sbin $ file sh
sh:             PA-RISC1.1 shared executable
ran:/sbin $ file /usr/bin/sh
/usr/bin/sh:    PA-RISC1.1 shared executable dynamically linked
ran:/sbin $

Why in /sbin? It belongs to root FS, not the case of the others (/usr on separate FS...)
It helps when in single user doing maintenance...
This User Gave Thanks to vbe For This Post:
jackliang
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