Convert variable to lower string and concatenate

Why this is not working:

MDB="user_"+${PROJECT | tr '[:upper:]' '[:lower:]'}
开发者_高级运维

Please help. Thanks.

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Are you familiar with chcase ?

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What are you trying to do? Are you attempting to translate whatever ${PROJECT} is into lower case before setting MDB?

MDB="user_$(echo ${PROJECT} | tr [:upper:] [:lower:])"

The $(..) tells the shell to execute the command and replace the text with the standard of that command.

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MDB="$(echo "user_$PROJECT" | tr '[:upper:]' '[:lower:]')"

(Note: the outer double-quotes aren't strictly necessary here, but there are a lot of places where leaving them out'll cause subtle bugs, so I tend to err on the side of overuse.)

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MDB="user_${PROJECT}" | tr "[:upper:]" "[:lower:]"

in bash

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Try this:

cat MDB="user_${PROJECT}| tr '[a-z]' '[A-Z]' > user_${PROJECT} // OR whatever you want to name your file.

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You have a slight syntax error in your bash script. Modify it just slightly so that it looks like the following:

MDB="$(echo "user_$PROJECT" | tr '[:upper:]' '[:lower:]')" 

Good luck!