Concatenate variables to a String bash script

Question

I am trying to Concatenate variables with Strings in my bash script, the variables are being read independently but whenever I try to concatenate them, it doesn't recognize the variable values. ex-

echo $CONFIG_PROTOCOL (Prints the variable value, HTTP) 

echo $CONFIG_PROTOCOL'://'$CONFIG_SERVER_SOURCE:$CONFIG_PORT'/api/creation/objects/export?collection.ids='$sf

The above echo with the URL prints out /api/creations/objects/export?collection.ids=value_1, while it should print out http://localhost:8080/api/creation/objects/export?collection.ids=value_1

Any inputs will be appreciated.

Bad problem description: "it doesn't work". Good problem description: "It writes out ://:/api/creation/objects/export?collection.ids= but I expected HTTP://example.com:8080/api/creation/objects/export?collection.ids=42, because as you can see from this paste from my terminal (etc etc)." Please edit your question and add a good problem description — that other guy
– that other guy, Commented Feb 21, 2018 at 20:30

that other guy · Accepted Answer · 2018-02-21 20:55:43Z

2

This happens because $CONFIG_PORT has a trailing carriage return. Here's a MCVE:

CONFIG_PROTOCOL="http"
CONFIG_SERVER_SOURCE="example.com"
CONFIG_PORT="8080"
sf="42"

# Introduce bug:
CONFIG_PORT+=$'\r'

echo $CONFIG_PROTOCOL'://'$CONFIG_SERVER_SOURCE:$CONFIG_PORT'/api/creation/objects/export?collection.ids='$sf

When executed, this prints:

/api/creation/objects/export?collection.ids=42

When you comment out the buggy line, you get:

http://example.com:8080/api/creation/objects/export?collection.ids=42

In both cases, echo will appear to show the correct values because echo is a tool for showing text to humans and not useful for showing the underlying data. printf '%q\n' "$CONFIG_PORT" will instead show it in an unambiguous format:

$ echo $CONFIG_PORT
8080

$ printf '%q\n' "$CONFIG_PORT"
$'8080\r'

The best way to fix this is to ensure that whatever supplies the value does so correctly. But the easiest way is to just strip them:

echo $CONFIG_PROTOCOL'://'$CONFIG_SERVER_SOURCE:$CONFIG_PORT'/api/creation/objects/export?collection.ids='$sf | tr -d '\r'

answered Feb 21, 2018 at 20:55

that other guy

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1 Comment

subhatt Over a year ago

Just at the same time, I was able to verify that I had properties file in DOS format. It was indeed the line endings causing the issue. Thanks much!

Jay Shankar Gupta · Accepted Answer · 2018-02-21 20:37:29Z

0

echo "$CONFIG_PROTOCOL://$CONFIG_SERVER_SOURCE:$CONFIG_PORT/api/creation/objects/export?collection.ids=$sf"

Try above echo statement

answered Feb 21, 2018 at 20:37

Jay Shankar Gupta

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1 Comment

subhatt Over a year ago

Doesn't work. It still prints /api/creations/objects/export?collection.ids=value_1

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