Shell Programming and Scripting

Of course it doesn't print anything as you didn't tell it to print anything. Do you know about the $SHELL variable?

Also echo is not a awk action statement you are probably after print:

Code:

$ ps -hp $$ | awk '{ echo $5 }'
$ ps -hp $$ | awk '{ print $5 }'
-bash

Is it really necessary to be admin, i.e. is there a disadvantage (for instance, some features not working) if one installs shells locally? At least with other programming languages (Perl, Ruby, Python, ...), if I'm on a centrally administered system where I don't have admin rights, I prefer to install them in my $HOME instead of requesting an admin to do this just for me, because I can then easier control the version I'm using etc.

Are there features in shells, which would cause trouble with this approach? I'm aware that if I'm not admin, I can't put any shell-specific startup file into /etc, but I would see it only as a minor issue.

the script below:

Code:

 #!/bin/ksh
  
 NAME=`basename $0 .sh`
Today=`date '+%Y%m%d'`
TIMESTAMP=`date +%H:%M:%S`
LOCAL_SERVER=`hostname`
 let countcla=0
 countcla=`expr ${countcla} + 1`
 echo "${NAME} ${Today} ${TIMESTAMP} ${LOCAL_SERVER} ${countcla}"
MYSHELL=$(ps -hp $$|awk '{print $5}')
echo "MYSHELL IS ${MYSHELL}"
MYSHELL=`ps -hp $$|awk '{print $5}'`
echo "MY NEW SHELL IS ${MYSHELL}"
exit

Doesn't matter what I put in the first line

Code:

#!/bin/ksh

or

Code:

#!/bin/bash

both are working. The different is only if

Code:

 #!/bin/bash

result is

Code:

 test 20170628 08:58:12 gbdted01.us.db.com 1
MYSHELL IS /bin/bash
MY NEW SHELL IS /bin/bash

if I make

Code:

 #!/bin/ksh

the result is

Code:

 test 20170628 08:58:56 gbdted01.us.db.com 1
MYSHELL IS /bin/ksh
MY NEW SHELL IS /bin/ksh

So, my question is: what do I have installed Korn shell or bash? Obviously, I don't have to change old shell scripts, they will work. However, what will be working better, faster and code easier, ksh or bash?
That is what I have to tell to my manager. If bash easy to code and work faster, then we can request to install bash rpm.

What would you propose?

Thanks for contribution

You have obviously both shells installed, and your code happens to be compatible to both (bash and ksh share a common language subset). Looking at your code, I guess it would also work with Zsh and Posix shell and even csh (but who wants to program in csh anyway). I don't know much about speed issues: Do you plan to write shell scripts which don't do much I/O, but mainly in-memory processing? If you are absolutely free to choose the shell, select the one which you like best. For instance, I consider Zsh most powerful and convenient from the programmer's point of view, but I know also programmers who say the same about bash or ksh.

Note also that you have to take account the version of the respective shell, because features change between versions. I would prefer working with a very recent bash over a very old Zsh....

As rovf says, you seem to have either installed.
Please be aware that your script will be executed in a subshell invoked with the interpreter named in the shebang (the very first line in the script if starting with EXACTLY #! - no space allowed as opposed to what you have in your example). So that doesn't say anything about your login shell. Try a simple echo $0 at the command prompt to see what that would be.

rovf, all our scripts are using I/O, we are reading files or getting data from database and cerate reports, some - small, some - huge.

RudiC

Code:

 echo $0

gives me

Code:

-ksh

If we have bash installed, I would go with bash, but it depends of big boss.
But what is you advise, which I can send to my manager use bash or use ksh? Of course the problem will get into "money" issue. If we have to change all scripts to bash, then I don't know if budget allows company to do it. Anyway, I need your advise what to tell my manager to persuade him to go with bash

Thanks for contribution