Here is my script:
#!/bin/bash
x="aabcaa"
y=${x##*(a)}
echo $y
It outputs aabcaa when I expect bcaa.
When I try the same commands on a bash shell (got with bash command from zsh shell), everything works as I want. I checked the version with bash --version and /bin/bash --version. Obviously, the two commands output the same thing. The unexpected behavior of the script is the same in a zsh shell and in a bash shell.
What could be wrong?
Related
I have a simple bash script test.sh
#!/bin/sh
# This is a comment
echo "Hi"
It does not execute anything when I try to run ./test.sh
$ ./test.sh
$
It comes with empty output. The mac terminal is executing echo commands but not shell script. I am not sure what I am missing. Please suggest.
to execute command file , type sh test.sh
I have a bash script that opens up a shell called salome shell and it should execute a command called as_run in that shell. The thing is that after entering the salome shell it doesn't execute the command until I exit the salome shell. This is the code that i got:
#!/bin/bash
cd /opt/salome/appli_V2018.0.1_public
./salome shell
eval "as_run /home/students/gbroilo/Desktop/Script/Template_1_2/exportSalome"
What should I do in order to execute the command in the salome shell?
Might be this is what you want:
# call salome shell with commands in a specified script file
cd /opt/salome/appli_V2018.0.1_public
./salome shell <"/home/students/gbroilo/Desktop/Script/Template_1_2/exportSalome"
Or might be this is what you want:
# pipe a command as_run... to salome shell
cd /opt/salome/appli_V2018.0.1_public
echo "as_run /home/students/gbroilo/Desktop/Script/Template_1_2/exportSalome" | ./salome shell
Anyway, you have to read the salome guide about how salome shell call it's script.
Most shells implement a way to pass the commands as parameters, e.g.
dash -c 'x=1 ; echo $x'
You'll need to consult your shell's manual to see if it's possible.
You can also try sending the commands to the standard input of the shell:
echo 'set x = 1 ; echo $x' | tcsh
Using a HERE doc might be a bit more readable in case of complex commands:
tcsh << 'TCSH'
set x = 1
echo $x
TCSH
I am attempting to store the result of an echo command as a variable to be used in a shell script. Debian 4.19.0-6-amd64
The command works in terminal: echo $HOSTNAME returns debian-base, the correct hostname.
I attempt to run it in a shell script, such as:
#!/usr/bin/bash
CURRENT_HOSTNAME=`echo $HOSTNAME`
echo $CURRENT_HOSTNAME
I have tried expansion:
CURRENT_HOSTNAME=$(echo $HOSTNAME)
And just to cover some more bases, I tried things like:
CURRENT_HOSTNAME=$HOSTNAME
# or
CURRENT_HOSTNAME="$HOSTNAME"
# also, in case a problem with reserved names:
test=$HOSTNAME
test="$HOSTNAME"
Works great in the terminal! Output is as follows:
root#debian-base:/scripts# echo $HOSTNAME
debian-base
root#debian-base:/scripts# TEST_HOSTNAME=$HOSTNAME
root#debian-base:/scripts# echo $TEST_HOSTNAME
debian-base
root#debian-base:/scripts# TEST_TWO_HOSTNAME=$(echo $HOSTNAME)
root#debian-base:/scripts# echo $TEST_TWO_HOSTNAME
debian-base
As soon as I run the script (as above):
root#debian-base:/scripts# sh test.sh
root#debian-base:/scripts#
What am I doing wrong?
You are using bash as your terminal. Bash has the variable $HOSTNAME set. You run your script with sh. sh does not have a $HOSTNAME.
Options:
bash test.sh
Or run it as a program:
chmod +x test.sh
./test.sh
But I think you need to change your first line to:
#!/bin/bash
As I don't think bash is installed in /usr/bin in most cases. But you need to try. To figure out where bash is installed use which bash
Another option is to use the hostname binary:
CURRENT_HOSTNAME=$(hostname)
echo $CURRENT_HOSTNAME
Which works in both bash and sh.
You can start sh by just running sh. You will see it has a bash-like terminal. You can try to do echo $HOSTNAME. It will not show, because it's not there. You can use set to see all the variables that are there (as sh does not have tab completion it's harder to figure out).
I want to execute Zsh function command in Bash script. Here is an example:
~/.zshrc
hello () {
echo "Hello!"
}
hello.sh
#!/bin/bash
hello
executing above bash script in zsh
(zsh) $ ./hello.sh
hello command not found
I also tried with heredocs:
#!/bin/bash
/bin/zsh - <<'EOF'
hello
EOF
executing above script with heredocs also says command not found error.
Any suggestions?
Thanks!
You can use it like that :
#!/bin/bash
/bin/zsh -i -c hello
-i : Force shell to be interactive
Then, if the shell is interactive, commands are read from /etc/zshrc and then $ZDOTDIR/.zshrc (this is usually your $HOME/.zshrc)
-c : Run a command in this shell
The default shell on the the system is csh but I want to write a script in bash. How do I write a script that will run bash and then convert back to csh at the end.
I tried this but it doesn't work:
bash
var=Hello
echo $var
csh
The command you are looking for is exit. When typing at the keyboard use exit instead of csh to get back to csh. When you enteredcsh, that just started a new csh session on top of the csh and bash sessions already running.
%bash
$ var=Hello
$ echo $var
Hello
$ exit
exit
%
As others have said, when using a script:
#! /bin/bash
var=Hello
echo $var
exit # You don't need exit; but it's okay here.
You don't need to change shells back again. When the script is run, it will be run by a sub-shell (which exits at the end of the script), and the parent shell is unchanged. So, as already suggested, the only thing you have to do is ensure the script is run by the correct shell, and the 'shebang' is the way to do that:
#!/bin/bash
var=Hello
echo $var
That's all it takes.
Define it using the sha bang
#!/bin/bash
at the starting of your file.