Read property from properties file within Shell Script

reading-property-from-file.sh

#!/bin/sh

PROPERTY_FILE=apps.properties

function getProperty {
   PROP_KEY=$1
   PROP_VALUE=`cat $PROPERTY_FILE | grep "$PROP_KEY" | cut -d'=' -f2`
   echo $PROP_VALUE
}

echo "# Reading property from $PROPERTY_FILE"
REPOSITORY_URL=$(getProperty "nexus.repository.url")

good job! thanks..
and for me this line worked --> PROP_VALUE=$(cat $PROPERTY_FILE | grep $PROP_KEY | cut -d'=' -f2)

This worked for me on all *nix platform:
PROP_VALUE=cat $PROPERTY_FILE | grep "$PROP_KEY" | cut -d'=' -f2

you can just source the file
source apps.properties
echo $PROP_KEY should give you value

you can just source the file
source apps.properties
echo $PROP_KEY should give you value

Will not work if any property key has dots, e.g. 'mail.alert.to=yourname@yourdomain.com'

Author's script won't work on property values that contain '=', case in point AES hash. Here is what I did,

get_property() {
        property=$(sed -n "/^[ tab]*$1[ tab]*/p" $2)
        if [[ $property =~ ^([ tab]*"$1"[ tab]*=)(.*) ]]; then
                echo ${BASH_REMATCH[2]}
        fi
}

As @adorogensky mentioned this won't work if the string itself contains a '='. Simply change '-f2' to '-f2-'
echo "asd=asd=asd" | cut -d'=' -f2 -> "asd"
echo "asd=asd=asd" | cut -d'=' -f2- -> "asd=asd"

From the man page:

The list option argument is a comma or whitespace separated set of numbers and/or number ranges. Number ranges consist of a number, a dash (`-'), and a second number and select the fields or columns from the first number to the second, inclusive. Numbers or number ranges may be preceded by a dash, which selects all fields or columns from 1 to the last number. Numbers or number ranges may be followed by a dash, which selects all fields or columns from the last number to the end of the line. Numbers and number ranges may be repeated, overlapping, and in any order. If a field or column is specified multiple times, it will appear only once in the output. It is not an error to select fields or columns not present in the input line.

`cat ${PROPERTY_FILE} | grep -w "$PROP_KEY" | cut -d'=' -f2``

All seems working for me. I did changes for Exact match of keys. grep with -w

It won't work when the property is commented out.

The trouble with all these suggestions is that the resulting value could have a newline character.

cat ${PROPERTY_FILE} | grep -w version | cut -d '=' -f 2 | tr -d '\n'

This script does not work when the variable and the value are the same.

prop1=prop1

The trouble with all these suggestions is that the resulting value could have a newline character.

cat ${PROPERTY_FILE} | grep -w version | cut -d '=' -f 2 | tr -d '\n'

You can also strip out carriage returns as follows:

cat "${PROPERTY_FILE}" | grep -w version | cut -d '=' -f 2 | tr -d '\n\r'

tr will treat the '\n\r' specification as a list of characters to delete (in any order, whether alone or together). Handy if your property file was created on a Windows system.

This script does not work when the variable and the value are the same.

Try this:

cat "${PROPERTY_FILE}" | grep --color=never "prop1=" | cut -d '=' -f 2 | tr -d '\n\r'

Requires the = to immediately follow the property name.