I have one script which runs in Bash and and other which runs in tcsh.
I need to run them both from the same script. How can I create a script that
can run both bash and tcsh commands?
Most shells have an argument which allow you to pass them a string to run as a command, for example, for bash you can run
bash -c "echo this is a bash script; echo lalalala"
to run that string as a script in bash, use this to run the needed shell embedded in the other. This will allow you to make a script in one shell which will invoke the other shell when the other program needs to be run.
If on the other hand they are both properly shebanged begin with #!tcsh or #!bash you can simply run both scripts from the same bash script using:
/path/to/script1 &
/path/to/script2 &
Related
I'm converting an app to a new image, and the existing commands use substring expansion to set the artifact version like so: mvn clean versions:set -DnewVersion="0.1.$VCSINFO.I${INFO:0:6}.M$OTHER_INFO". I'm using a ubuntu image that defaults to /bin/sh, and I am unable to figure out how to either do something equivalent in bourne shell, or switch shells to run the command. I know bash is installed because I can see it in /etc/shells.
I tried using RUN ['/bin/bash', '-c', '...'] but I can see it is just running that command like so The command '/bin/sh -c ['/bin/bash', '-c',.... What is the best way to convert this functionality over to this new image?
You can run a bash command in two ways, even from sh: Either by passing the string '/bin/bash path/to/your/cmd' to the -c option of sh, or by setting the x-bit in cmd and having as the first line in cmd a #!/bin/bash.
Hence in your setting I would try either a RUN ['/bin/bash /path/to/your/cmd'] or just do a RUN ['/path/to/your/cmd'] and ensure that cmd has the #! line mentioned above, or complicated but fail safe - write a sh wrapper script, which then invokes the bash script in turn. Hence, if this wrappe script is called /path/to/your/cmdwrapper.sh, its content would be
:
/bin/bash /path/to/your/cmd
So I have a few tcsh scripts associated with an expensive software that I have to run them on a bash shell system. Is that even possible? This software needs these scripts frequently and is based on tcsh. Is it possible to run 2 shells at the same time? Or just call tcsh shell at the beginning of the script? or is there any compiler to translate the shell scripts? What are my options? Thank you.
Simply put a proper shebang at the top of the script.
Assuming your tcsh is installed as /bin/tcsh, each tcsh script should have this as its first line:
#!/bin/tcsh -f
(The -f tells the shell not to load your startup scripts such as .login or .tcshrc. Any script shouldn't depend on your user environment, so you don't need to invoke your startup scripts -- and it will make your scripts load faster. Note that -f has a different meaning for Bourne-derived shells; use -f only for csh and tcsh scripts.)
If you can't portably assume where tcsh is installed, an alternative is:
#!/usr/bin/env tcsh
But that doesn't let you use the -f option, and it could have other disadvantages; see this answer for details.
Note that there really isn't such a thing as a "bash shell system". Both bash and tcsh are just programs that you can run. One or the other might happen to be the default interactive shell for newly created user accounts, but that doesn't affect being able to run either of them.
I am trying to play with bash and arrays. But executing a sample script, I got an unexpected syntax error message: example.sh: 3: example.sh: Syntax error: "(" unexpected. And this is the script
#!/bin/bash
array=( one two three )
If I run the script with ./example.sh it works and no errors are displayed. But if I run sh example.sh I get the error message.
I thought that these two commands are the same:
sh example.sh
./example.sh
so ... what is the difference between the two?
When you launch it via ./example.sh then the command specified in the first line of the script is used to interpret the content. So your script executes in a bash, where such syntax is allowed for arrays.
When you launch it via sh example.sh then sh is the command that is used to interpret the content of the file. sh is the original Unix shell (aka Bourne shell) and this shell is a little more rude than bash (Bourne again shell). You don't have such arrays. Note that in sh the first line of your script is just interpreted as a comment.
by using sh example.sh
- you are specifying what shell interpreter to use for that script. Example being "bash example.sh" instead of "sh example.sh" etc etc.
Running scripts this way disregards the "shebang (#!/bin/bash)" that you have specified inside of the script. Since you wrote a bash script but are trying to run it as just "sh", this is why it is failing
by using ./example.sh,
- You are specifying to run the script from your current directory. This will attempt to run the script in whatever shell you are currently in unless a shebang is specified. Since you have a "shebang" specified to run the script in bash... this is why it is working.
array_name=(value1 ... valuen)
This is how to initializes an array in bash only. When you execute ./example.sh, the shebang line #!/bin/bash tells the system to use bash to execute.
However, when you execute sh example.sh, sh is used to execute. In many Unix systems (like Linux), sh is equivalent to bash. It seems sh is a different shell on your system.
I have some shell scripts which I run in my Linux/AIX machine with bash profile. Now my bash profile is going to be remove, and I will have Korn shell (ksh) or the C shell (csh). How to verify whether my scripts will run fine in Korn shell (ksh) or C shell (csh), even after bash shell is removed. Also, is there any differnce in commonly used commands between bash and other (ksh, csh). Is there command to check, which shell is getting used while running the shell script.
First of all, this is not a problem, the default shell of your account is irrelevant. As long as bash is installed on the machine, you can use it to run your code. Either add a shebang line as the first line of your script:
#!/usr/bin/env bash
Or, explicitly run the script with bash:
$ /bin/bash /path/to/script.sh
As for the differences, yes there are many. A script written for bash will not run in csh, their syntax is completely different. It might run on ksh but that will depend on your script. Not all features of the two shells are the same. For example:
$ cat test.sh
var="foo";
echo $var;
$ bash ./test.sh
foo
$ ksh ./test.sh
foo
$ csh ./test.sh
var=foo: Command not found.
var: Undefined variable.
As you can see above, var=foo runs correctly in ksh (which is part of the bourne shell family) but fails for csh. Basically, think of each shell as its own programming language. You wouldn't expect the python interpreter to be able to run a perl program, why do you expect one shell to be able to run a script written for another?
OP writes bash is going to be removed.
If you really cannot get bash installed. start each script with #!/bin/ksh and check for syntax problems:
ksh -n migrated_script
When you use bash/linux specific things you need to address them:
AIX will be "missing" flags on commands like find (changed last hour...) and ksh itself is also different.
Do not try csh, that is completely different.
I have a bash script .sh which needs to be executed as a Target Simulator in Eclipse. The problem is, if I run the script with sh run.sh command in terminal, it throws Bad Substitution error. But it works perfectly with bash run.sh. Apparently, Eclipse run it with sh command cause it gives the same error in console. But how can I make Eclipse to run the script with bash instead?
I'm on Ubuntu 13.10.
bash and sh aren't the same shell. There are many constructs valid in bash that are not understood by sh.
Have you provided a correct sheebang as the first line of your script?
#!/bin/bash
If so -- and if Eclipse insist on running script with sh, you still have the option of wrap your script in a heredoc and pass it to bash explicitly:
sh$ cat run.sh
bash << EOF
#
# Here is your bash script
#
EOF
This is mostly a hack until you find how to instruct Eclipse of using the right shell. I'm sure there is a way!