/dev/chat

12:40 AM

@Kusalananda Does source script first ensures the right syntax of complete script before executing it?

where as ./script parses and executes line by line.

2:41 AM

#!/bin/sh
cd /a/b/c
con_command # gives error - con_command is located in /a/b/c folder
./con_command # works fine

in Linux

But in solaris 10

below code works fine

#!/usr/bin/ksh
cd /a/b/c
con_command # works fine

Kusalananda

6:30 AM

@overexchange You know that $PATH determines where the cemmands will be taken from if no explicit path is given to the command on the command line.

Kusalananda

7:49 AM

@overexchange Depending on whether con_command is a script or a function, the FPATH variable may also come into play. You really need to read and understand the script you are porting from Solaris to Linux, especially if you are porting it to a new shell.

overexchange

8:03 AM

ok

@Kusalananda Does bash read .profile? Because I set some environment variable in .profile but it does not take into effect

Kusalananda

@overexchange It does, but only if there is no .bash_profile.

overexchange

ok ok

Kusalananda

... but only when invoked as a login shell.

overexchange

hmm... am trying to understand serverfault.com/a/376264/220043

login shell

Kusalananda

253

Q: Difference between Login Shell and Non-Login Shell?

I understand the basic difference between an interactive shell and a non-interactive shell. But what exactly differentiates a login shell from a non-login shell? Can you give examples for uses of a non-login interactive shell?

overexchange

8:08 AM

we actually do sudo su - username and then start application

so this is login shell

@Kusalananda So... basically 1) I have ksh88 running scripts in solaris 10 with shebang line #!/usr/bin/ksh 2) /bin/sh -> /sbin/sh Bourneshell running scripts in solaris 10 with shebang line #!/bin/sh

I need to port these two categories of scripts to Linux box that has ksh93 and /bin/sh -> bash

Looks like there is no bourne shell in RHELinux box

I do not want to change the shebang lines...

and port the scripts from solaris to Linux

Kusalananda

Porting is difficult. I can't say "do this and it will work". You will have to read and understand the scripts, and then reimplement the things that work differently between the two systems. There are no shortcuts.

I can't emphasise this enough, you absolutely have to look at every single line of the scripts that you port to make sure that you understand what it is doing on Solaris and what it would do on Linux running under a different shell.

You have to understand how sh and ksh works on Solaris and you have to understand how sh works on your Linux system.

overexchange

8:25 AM

/bin/sh -> /bin/bash in Linux which is bash shell

/bin/sh -> /sbin/sh in solaris 10, which is bourneshell

Kusalananda

Both are sh, so the syntax, grammar, and shell initialisation etc. should be similar.

overexchange

One is bourneshell and other is bash shell.. aren't they different?

27

A: Difference between sh and bash

Shell is an interface between a user and OS to access to an operating system's services. It can be either GUI or CLI (Command Line interface). sh (Bourne shell) is a shell command-line interpreter, for Unix/Unix-like operating systems. It provides some built-in commands. In scripting language we...

Kusalananda

@overexchange sh on your Linux is bash running in POSIX compatibility mode, i.e. as if bash --posix was used. You should really be looking at the bash manual.

overexchange

8:55 AM

ok

terdon

9:35 AM

@overexchange anything written for bourne shell will work fine on bash. The problem is translating bash stuff to bourne, not bourne stuff to bash.

Essentially, bash contains sh, so anything that sh understands, bash will understand also.

Kusalananda

9:46 AM

@terdon You also have to take the Solaris environment into account, and how it differs from Linux. You simply can't say "this script will work on Linux, because it uses sh".

If he's porting an application (that is evidently running as root), and he's doing it as part of his job, then assuming that the scripts will work because they use the same shell variant is both negligent and dangerous.

Stephen Kitt

Urgh yes, in a previous life I had to write shell scripts which would work on ksh88 on Solaris, ksh93 (IIRC) on AIX, and bash on Linux. There are significant, non-shell-related differences between all three. The answer really depends on what the shell script is supposed to do...

Kusalananda

Using sh on both systems does make it easier though. It allows one to look at environmental differences instead of porting syntax and grammar.

terdon

10:09 AM

@Kusalananda No, I just mean the script will run and the syntax won't need to be changed. Now, whether or not the scripts will do what they are supposed to is another matter.

Tim

1:53 PM

@StephenKitt Thanks. (1) In C, when does execution of function definitions happen?

(2) In all these languages, what is "execution of function definitions"? What result is "execution of function definitions " expected to generate? In all these languages, is "execution of function definitions " expected to create a "link" between the function names and their implementations, so that when executing a function call the interpreter can find the function implementation? Is this linking in C, interpretation in Bash, and compilation in awk?

overexchange

2:35 PM

@terdon what about ksh88(Solaris 10) to ksh93(Rhel 7.5) porting?

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