Need to write a program to sanely configure a login shell - bash

I just started using a Solaris 10 (Sparc) box where I telnet in and get confronted with a very unfriendly interface (compared to the standard bash shell I use in cygwin or linux) --- the arrow keys do not work as I expect them to. Being an NIS system, changing the shell is not as easy as using the "chsh" command. And setting the SHELL environment variable in ~/.login and ~/.profile is not working for me. So I'm thinking that I may need to write a script to determine if bash is running the script and starting bash if the answer is no. My first attempt, trying to invoke /bin/bash from ~/.profile seems to work but kind of doesn't feel right. Other suggestions? And how do I tell programmatically which shell is actually executing?

You can tell what shell is running with echo $0. For example:
$ echo $0
-bash
If you're changing shell you probably want to replace the current shell process rather than be a child of it, so use exec.
Also, you want to pass bash the -l flag so it acts as if it has been called as part of the login process.
So you'll want something like:
exec bash -l

You are probably running with ksh(1) on Solaris. You have several options, read the manpage for ksh and configure it or install another shell you're more familiar with like bash. I'd personnaly recommend zsh.

Related

bash command in server startup

I am trying to run a server. the command x_server.sh do not work for my ubuntu 14.04 but it runs when I give the command bash x_server.sh.
It has adviced that the products should not run as a daemon thread.
What I want to know is what exactly this bash command do, is it run as a daemon thread when i do so and what are the alternative ways there for me to use to make that command x_server.sh work.
On Ubuntu the default shell is Dash, not Bash. Presumably your x_server.sh script starts like this:
#!/bin/sh
You should change it to this:
#!/usr/bin/env bash
That will make it auto-select the best "bash" on the system rather than the default shell which is dash which has different (mostly fewer) features than bash.
And of course you need to do the usual chmod +x x_server.sh to make it executable in the first place, and run it as ./x_server.sh unless it's in your $PATH.

Unable to execute shell script in Cygwin as a KornShell script

I rarely touch shell scripts, we have another department who write them, so I have an understanding of writing them but no experience. However they all appear rather useless with my issue.
I am trying to execute some KornShell (ksh) scripts on a windows based machine using Cygwin- we use these to launch our Oracle WebLogic servers, now it simply will not execute. I used to be able to execute these exact same scripts fine on my old machine.
Now I have narrowed this down to the fact the 'magic number' or whatever it is at the start of the script where it specifies the script interpreter path:
i.e.:
#!/bin/ksh
if I change it to execute as a simple bash it works i.e:
#!/bin/sh
I went through checking the packages installed for cygwin - now the shells I installed are:
mksh MirdBSD KornShell
bash the bourne again shell
zsh z shell
Should I expect to see a ksh.exe in my cygwin/bin directory? there is a system file 'ksh' which I was making an assume somehow associates it with one of the other shell exes, like mksh.exe
I understand my explanation may well be naff. But that being said, any help would be very much appreciated.
Thanks.
I believe the MirBSD korn shell is called mksh. You can verify this and look for the correct path by typing
% which mksh
% which ksh
or if you have no which,
% type -p mksh
% type -p ksh
or if that fails too, check /etc/shells which should list all valid shells on a system:
% grep ksh /etc/shells
You need to put the full path after the #! line. It will probably be /bin/mksh, so your line needs to look like:
#!/bin/mksh
You've probably fixed it by now, but the answer was no, your Cygwin does not (yet) know about ksh.
I solved this problem by launching the cygwin setup in command-line mode with the -P ksh attribute (as described in http://www.ehow.com/how_8611406_install-ksh-cygwin.html).
You can run a ksh using a bat file
C:\cygwin\bin\dos2unix kshfilename.ksh
C:\cygwin\bin\bash kshfilename.ksh
Running a shell script through Cygwin on Windows
Install KornShell (ksh) into Cygwin by the following process:
Download: ksh.2012-08-06.cygwin.i386.gz
Install ksh via Cygwin setup.
Execture Cygwin setup.exe
Choose: Install from Local Directory
Select the ksh.2012-08-06.cygwin.i386.gz as the Local Package Directory.
Complete Cygwin setup.
Restart Cygwin.

How do I tell what type my shell is

How can I tell what type my shell is? ie, whether it's traditional sh, bash, ksh, csh, zsh etc.
Note that checking $SHELL or $0 won't work because $SHELL isn't set by all shells, so if you start in one shell and then start a different one you may still have the old $SHELL.
$0 only tells you where the shell binary is, but doesn't tell you whether /bin/sh is a real Bourne shell or bash.
I presume that the answer will be "try some features and see what breaks", so if anyone can point me at a script that does that, that'd be great.
This is what I use in my .profile:
# .profile is sourced at login by sh and ksh. The zsh sources .zshrc and
# bash sources .bashrc. To get the same behaviour from zsh and bash as well
# I suggest "cd; ln -s .profile .zshrc; ln -s .profile .bashrc".
# Determine what (Bourne compatible) shell we are running under. Put the result
# in $PROFILE_SHELL (not $SHELL) so further code can depend on the shell type.
if test -n "$ZSH_VERSION"; then
PROFILE_SHELL=zsh
elif test -n "$BASH_VERSION"; then
PROFILE_SHELL=bash
elif test -n "$KSH_VERSION"; then
PROFILE_SHELL=ksh
elif test -n "$FCEDIT"; then
PROFILE_SHELL=ksh
elif test -n "$PS3"; then
PROFILE_SHELL=unknown
else
PROFILE_SHELL=sh
fi
It does not make fine distinctions between ksh88, ksh95, pdksh or mksh etc., but in more than ten years it has proven to work for me as designed on all the systems I were at home on (BSD, SunOS, Solaris, Linux, Unicos, HP-UX, AIX, IRIX, MicroStation, Cygwin.)
I don't see the need to check for csh in .profile, as csh sources other files at startup.
Any script you write does not need to check for csh vs Bourne-heritage because you explicitly name the interpreter in the shebang line.
Try to locate the shell path using the current shell PID:
ps -p $$
It should work at least with sh, bash and ksh.
If the reason you're asking is to try to write portable shell code, then spotting the shell type, and switching based on it, is an unreliable strategy. There's just too much variation possible.
Depending on what you're doing here, you might want to look at the relevant part of the autoconf documentation. That includes an interesting (and in some respects quite dismal) zoology of different shell aberrations.
For the goal of portable code, this section should be very helpful. If you do need to spot shell variants, then there might be some code buried in autoconf (or at least in one of the ./configure scripts it generates) which will help with the sniffing.
You can use something like this:
shell=`cat /proc/$$/cmdline`
Oh, I had this problem. :D
There is a quick hack, use ps -p $$ command to list the process with PID of the current running process -- which is your SHELL. This returns a string table structure, if you want, you can AWK, or SED the shell out...
The system shell is the thing you see when you open up a fresh terminal window which is not set to something other than bash (assuming this is your default SHELL).
echo $SHELL
Generally, you can find out all the constants defined by running
set
If the output is a lot of stuff then run
set | less
so you can scroll it from the top of the command line or
set > set.txt
To save the output to a file.
Invoking a different interactive shell to bash in your terminal does not mean that your system shell gets changed to something else i.e. your system shell is set to bash although you invoke a csh shell from a bash shell just that one session.
The above means that typing /bin/csh or /bin/python in bash or whatever does not set the system shell to the shell you invoked, at all.
If you really want to see the SHELL constant change then you need to set it to something else. If successful you should see the new shell whenever you open a fresh terminal...
It's old thread but...
In GNU environment You can sh --help and get something like
BusyBox v1.23.2 (2015-04-24 15:46:01 GMT) multi-call binary.
Usage: sh [-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]
Unix shell interpreter
So, the first line is shell type =)

How to get a bash instance with loaded default profiles within objective-C

Problem:
I want to be able to run a bash instance from my cocoa application (OS X) with all the normal profiles loaded (~/.bash_profile, etc). I don't want to load the profiles manually since I want to have a default bash instance that is exactly the same as one you would get by firing terminal. From there, I'd like to retrieve some pre-defined environment variable (Ruby version manager's variables).
What I've tried:
I've already tried some solutions with no success. Let me list them here:
NSTask
system() call
for every solutions I tried to execute "/bin/sh -l" to have a bash instance loaded as the current username... unfortunately it didn't work.
When you run bash as sh, it runs in a compatibility mode where it doesn't read .bash_profile. If you want to run bash then run /bin/bash (or if you want other people to use your application, make sure you account for whatever shell the user has selected.)
You can use the command line option '--login' to tell bash to behave as a login shell.
Classically, a shell would act as a login shell if the basename of its argv[0] started with a dash.
You might be able to get the required effect with:
bash --login -c 'echo $RUBY_VARIABLE_OF_INTEREST'
If you are doing this with popen(), you can read the output from the shell.

How do I specify the shell to use for a ruby system call?

I am trying to run commands from ruby via system (or by using backticks), but am running into problems. When I try to call a command, the shell is unable to find it, even though I know it works if I call it straight. For example:
`zip`
>> sh: zip: command not found
The problem seems to be that ruby is using the sh shell, in which $PATH is not set correctly, rather than bash, and I am not sure why. The user my application is running under is set up to use bash by default.
Is there any way to tell ruby to use bash instead of sh?
As far as I know, the only way to do that is to explicitly invoke the shell, e.g.
`bash -c zip`
or
`#{ ENV['SHELL'] } -c zip`
Or with system: system("bash", "-c", command)
However ruby (and all processes spawned by ruby) should inherit the parent processes' environment and thus have $PATH set correctly even when using another shell. Do you maybe run ruby from a cron job or init script or the like, where PATH is simply not set correctly?
i'm guessing that Ruby uses the system() C function, which uses /bin/sh. In most systems, /bin/sh is just a symlink to other shell, so you can change to whatever you want
Why not just specify the full path the the zip executable.

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