Eval and exec with variable substitution
I'd like to execute a statement to start a server. For that I have an environment variable to determine which server is to be started. I was given this command as a starting point:
eval "exec gunicorn --chdir /this/dir package.sub:call_main() -b 0.0.0.0:80"
As I have a few kinds of servers to start up, I would like to parameterise the script. And after searching around, I found out the quotations are redundant. So what I have now is:
APP=main
eval exec gunicorn --chdir /this/dir package.sub:call_${APP}() -b 0.0.0.0:80
This, however produces a syntax error near unexpected token '('. Ideally I would even like to have a default argument like ${APP:-main}, but I guess that is possible once the syntax error issue is resolved.
What is wrong with the statement above? Additionally, is eval or even exec needed here?
bash terminal environment-variables exec eval
asked 7 mins ago
FelixFelix
1011
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I'd like to execute a statement to start a server. For that I have an environment variable to determine which server is to be started. I was given this command as a starting point:
eval "exec gunicorn --chdir /this/dir package.sub:call_main() -b 0.0.0.0:80"
As I have a few kinds of servers to start up, I would like to parameterise the script. And after searching around, I found out the quotations are redundant. So what I have now is:
APP=main
eval exec gunicorn --chdir /this/dir package.sub:call_${APP}() -b 0.0.0.0:80
This, however produces a syntax error near unexpected token '('. Ideally I would even like to have a default argument like ${APP:-main}, but I guess that is possible once the syntax error issue is resolved.
What is wrong with the statement above? Additionally, is eval or even exec needed here?
bash terminal environment-variables exec eval
asked 7 mins ago
FelixFelix
1011
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I'd like to execute a statement to start a server. For that I have an environment variable to determine which server is to be started. I was given this command as a starting point:
eval "exec gunicorn --chdir /this/dir package.sub:call_main() -b 0.0.0.0:80"
As I have a few kinds of servers to start up, I would like to parameterise the script. And after searching around, I found out the quotations are redundant. So what I have now is:
APP=main
eval exec gunicorn --chdir /this/dir package.sub:call_${APP}() -b 0.0.0.0:80
This, however produces a syntax error near unexpected token '('. Ideally I would even like to have a default argument like ${APP:-main}, but I guess that is possible once the syntax error issue is resolved.
What is wrong with the statement above? Additionally, is eval or even exec needed here?
bash terminal environment-variables exec eval
asked 7 mins ago
FelixFelix
1011
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'd like to execute a statement to start a server. For that I have an environment variable to determine which server is to be started. I was given this command as a starting point:
eval "exec gunicorn --chdir /this/dir package.sub:call_main() -b 0.0.0.0:80"
As I have a few kinds of servers to start up, I would like to parameterise the script. And after searching around, I found out the quotations are redundant. So what I have now is:
APP=main
eval exec gunicorn --chdir /this/dir package.sub:call_${APP}() -b 0.0.0.0:80
This, however produces a syntax error near unexpected token '('. Ideally I would even like to have a default argument like ${APP:-main}, but I guess that is possible once the syntax error issue is resolved.
What is wrong with the statement above? Additionally, is eval or even exec needed here?
bash terminal environment-variables exec eval
bash terminal environment-variables exec eval
asked 7 mins ago
FelixFelix
1011
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 7 mins ago
FelixFelix
1011
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 7 mins ago
FelixFelix
1011
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 7 mins ago
FelixFelix
1011
asked 7 mins ago
FelixFelix
1011
1011
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Felix is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
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In your second piece of code, you have removed the double quotes around the argument to eval. Don't do that. Removing them would make () special to the shell (it starts a sub-shell).
Instead:
APP=main
eval "exec gunicorn --chdir /this/dir package.sub:call_$APP() -b 0.0.0.0:80"
Note that ${APP} and $APP is identical in every way except when immediately followed by a character that is valid in a variable name (as in "${APP}x"). Here, the {...} is not needed.
I'm uncertain why you want the exec in there, it doesn't seem neccesary.
answered 1 min ago
KusalanandaKusalananda
128k16241398
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1 Answer
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1 Answer
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In your second piece of code, you have removed the double quotes around the argument to eval. Don't do that. Removing them would make () special to the shell (it starts a sub-shell).
Instead:
APP=main
eval "exec gunicorn --chdir /this/dir package.sub:call_$APP() -b 0.0.0.0:80"
Note that ${APP} and $APP is identical in every way except when immediately followed by a character that is valid in a variable name (as in "${APP}x"). Here, the {...} is not needed.
I'm uncertain why you want the exec in there, it doesn't seem neccesary.
answered 1 min ago
KusalanandaKusalananda
128k16241398
add a comment |
In your second piece of code, you have removed the double quotes around the argument to eval. Don't do that. Removing them would make () special to the shell (it starts a sub-shell).
Instead:
APP=main
eval "exec gunicorn --chdir /this/dir package.sub:call_$APP() -b 0.0.0.0:80"
Note that ${APP} and $APP is identical in every way except when immediately followed by a character that is valid in a variable name (as in "${APP}x"). Here, the {...} is not needed.
I'm uncertain why you want the exec in there, it doesn't seem neccesary.
answered 1 min ago
KusalanandaKusalananda
128k16241398
add a comment |
In your second piece of code, you have removed the double quotes around the argument to eval. Don't do that. Removing them would make () special to the shell (it starts a sub-shell).
Instead:
APP=main
eval "exec gunicorn --chdir /this/dir package.sub:call_$APP() -b 0.0.0.0:80"
Note that ${APP} and $APP is identical in every way except when immediately followed by a character that is valid in a variable name (as in "${APP}x"). Here, the {...} is not needed.
I'm uncertain why you want the exec in there, it doesn't seem neccesary.
answered 1 min ago
KusalanandaKusalananda
128k16241398
In your second piece of code, you have removed the double quotes around the argument to eval. Don't do that. Removing them would make () special to the shell (it starts a sub-shell).
Instead:
APP=main
eval "exec gunicorn --chdir /this/dir package.sub:call_$APP() -b 0.0.0.0:80"
Note that ${APP} and $APP is identical in every way except when immediately followed by a character that is valid in a variable name (as in "${APP}x"). Here, the {...} is not needed.
I'm uncertain why you want the exec in there, it doesn't seem neccesary.
answered 1 min ago
KusalanandaKusalananda
128k16241398
answered 1 min ago
KusalanandaKusalananda
128k16241398
answered 1 min ago
KusalanandaKusalananda
128k16241398
answered 1 min ago
KusalanandaKusalananda
128k16241398
128k16241398
add a comment |
add a comment |
Felix is a new contributor. Be nice, and check out our Code of Conduct.
Felix is a new contributor. Be nice, and check out our Code of Conduct.
Felix is a new contributor. Be nice, and check out our Code of Conduct.
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