Adding or updating a configuration entry in / etc / environment

Question

My / etc / environment looks like this:

cat /etc/environment
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"

I want to use the command (sed, awk, python, whatever ....), which will look like this:

cat /etc/environment
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
JAVA_HOME="/usr/lib/jvm/java-6-sun"

Now you will understand that I would prefer to be 1 airliner (in the sed -XYZ / DoMagic // etc / environment fields), it should contain the merge logic - either add a new configuration entry or update an existing one. Bottom line, it should prevent the file from looking like this: (called in experimental shell scripts that call echo → on every call)

cat /etc/environment
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
JAVA_HOME="/usr/lib/jvm/java-5-sun"
JAVA_HOME="/usr/lib/jvm/java-6-sun"
JAVA_HOME="/usr/lib/jvm/java-6-sun"
JAVA_HOME="/usr/lib/jvm/java-6-sun"

I assume these are trigger questions because I am trying to avoid using custom scripts such as

/usr/local/bin/PropUpdate /etc/environment JAVA_HOME "/usr/lib/jvm/java-6-sun"

---

/usr/local/bin/PropUpdate - script ( , . )

#!/bin/bash

# Append/Update a configuration record in a file
#
# Usage example:
# /usr/local/bin/PropUpdate /etc/environment JAVA_HOME "/usr/lib/jvm/java-6-sun"
#
# Author Maxim Veksler <[e-mail]>
# Version 0.5-2010-07-27


EXPECTED_ARGS=3
E_BADARGS=3
E_BADFILE=4

if [[ $# -ne ${EXPECTED_ARGS} ]]; then
  echo "Usage: `basename $0` /path/to/config.conf ParameterName newValueText" >&2
  exit $E_BADARGS
fi

CONFIGURATION_FILE="$1"
CONFIGURATION_PARAMETER="$2"
CONFIGURATION_VALUE="$3"

if [[ ! -e "${CONFIGURATION_FILE}" ]]; then
        echo "Configuration file ${CONFIGURATION_FILE} does not exist" >&2
        exit $E_BADFILE
fi

if [[ ! -w "${CONFIGURATION_FILE}" ]]; then
        echo "Can't modify ${CONFIGURATION_FILE}" >&2
        exit $E_BADFILE
fi



#########################################
## Decide what parameter we are adding ##
#########################################
__param_found=0

# First check CONFIGURATION_PARAMETER supplied by use that contains "="
if [[ ${CONFIGURATION_PARAMETER} == *=* ]]; then
        # It should exist in the file, plain
        if grep -qE "^${CONFIGURATION_PARAMETER}" "${CONFIGURATION_FILE}"; then
                __param_found=1
                SUFFIX_REGEX='[[:space:]]*'
        fi
else
        # OK, sophisticated user, did not send "=" with the parameter...
        if grep -qE "^${CONFIGURATION_PARAMETER}[[:space:]]*=" "${CONFIGURATION_FILE}"; then
                # Let check if such configuration with Parameter + "=" exists
                __param_found=1
                SUFFIX_REGEX='[[:space:]]*=[[:space:]]*'
        elif grep -qE "^${CONFIGURATION_PARAMETER}[[:space:]]+" "${CONFIGURATION_FILE}"; then
                # If such parameter exists, at all
                __param_found=1
                SUFFIX_REGEX='[[:space:]]\+'
        fi
fi


if [[ $__param_found == 1 ]]; then
        #echo sed -i "s|^\(${CONFIGURATION_PARAMETER}${SUFFIX_REGEX}\).*$|\1${CONFIGURATION_VALUE}|g" "${CONFIGURATION_FILE}"
        sed -i "s|^\(${CONFIGURATION_PARAMETER}${SUFFIX_REGEX}\).*$|\1${CONFIGURATION_VALUE}|g" "${CONFIGURATION_FILE}"

else
        if [[ ${CONFIGURATION_PARAMETER} == *=* ]]; then
                # Configuration parameter contains "=" in it name, good just append
                echo "${CONFIGURATION_PARAMETER}${CONFIGURATION_VALUE}" >> "${CONFIGURATION_FILE}"
        else
                # Try to guess if this file is a "param = value" or "param value" type of file.
                if grep -qE "^[[:alnum:]]+[[:space:]]*=" "${CONFIGURATION_FILE}"; then
                        # Seems like a "param = value" type of file
                        echo "${CONFIGURATION_PARAMETER}=${CONFIGURATION_VALUE}" >> "${CONFIGURATION_FILE}"
                else
                        # Seems like a "param  value" type of file
                        echo "${CONFIGURATION_PARAMETER} ${CONFIGURATION_VALUE}" >> "${CONFIGURATION_FILE}"
                fi
        fi
fi

#cat $CONFIGURATION_FILE

, .

- : script, . , . .

Answer 1

, /etc/environment , /etc/profile.d/, . , . , .

Answer 2

grep -q JAVA_HOME /etc/environment || echo 'JAVA_HOME="/usr/lib/jvm/java-5-sun"' >> /etc/environment

grep 0 (true), . , :

, JAVA_HOME
JAVA_HOME

0-15:49 root@noneedto ~# cat /etc/environment
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
0-15:49 root@noneedto ~# grep JAVA_HOME /etc/environment && echo true
1-15:49 root@noneedto ~# grep -q JAVA_HOME /etc/environment || echo 'JAVA_HOME="/usr/lib/jvm/java-5-sun"' >> /etc/environment
0-15:49 root@noneedto ~# grep JAVA_HOME /etc/environment && echo true
JAVA_HOME="/usr/lib/jvm/java-5-sun"
true
0-15:49 root@noneedto ~# grep -q JAVA_HOME /etc/environment || echo 'JAVA_HOME="/usr/lib/jvm/java-5-sun"' >> /etc/environment
0-15:49 root@noneedto ~# cat /etc/environment
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
JAVA_HOME="/usr/lib/jvm/java-5-sun"

, , , grep true, .

Answer 3

Ubuntu JAVA_HOME :

JAVA_HOME=/usr/lib/jvm/default-java

ls -l /usr/lib/jvm/default-java, :

lrwxrwxrwx 1 root root 24 Apr 27  2012 /usr/lib/jvm/default-java -> java-1.7.0-openjdk-amd64

, - , .

Java, ls -l ...:

prompt$ ls -l /usr/lib/jvm
total 20
lrwxrwxrwx 1 root root   24 Apr 27  2012 default-java -> java-1.7.0-openjdk-amd64
drwxr-xr-x 4 root root 4096 Feb 23 17:54 java-1.5.0-gcj-4.8-amd64
lrwxrwxrwx 1 root root   20 Sep  2  2012 java-1.6.0-openjdk-amd64 -> java-6-openjdk-amd64
lrwxrwxrwx 1 root root   20 Jul  3  2013 java-1.7.0-openjdk-amd64 -> java-7-openjdk-amd64
drwxr-xr-x 5 root root 4096 Oct  7  2012 java-6-openjdk-amd64
drwxr-xr-x 3 root root 4096 Oct  7  2012 java-6-openjdk-common
drwxr-xr-x 5 root root 4096 Sep 21 20:06 java-7-openjdk-amd64
drwxr-xr-x 8 root root 4096 Sep 18 21:18 java-7-oracle

, :

sudo rm /usr/lib/jvm/default-java
sudo ln -s java-7-oracle /usr/lib/jvm/default-java

JAVA_HOME Java 7 Oracle.