Created
December 13, 2012 19:04
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An /etc/hosts manager bash script (v1.1) -- Added import and export commands!
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| #!/bin/bash | |
| HOSTSFILE="/etc/hosts" | |
| BAKFILE="$HOSTSFILE.bak" | |
| DOMAINREGEX="^[a-zA-Z0-9]{1}[a-zA-Z0-9\.\-]+$" | |
| IPREGEX="^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$" | |
| LINEREGEX="^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\s+$2" | |
| backup() | |
| { | |
| echo "Backup created at $BAKFILE"; | |
| cat $HOSTSFILE > $BAKFILE | |
| } | |
| usage() | |
| { | |
| echo "Usage:" | |
| echo "etchosts add [host] [ip]" | |
| echo "etchosts remove [host]" | |
| echo "etchosts update [host] [ip]" | |
| echo "etchosts check [host]" | |
| echo | |
| } | |
| isroot() | |
| { | |
| # Check for root user | |
| if [ $(whoami) != "root" ]; then | |
| echo "$0 must be run as root... Aborting."; echo; | |
| exit 192 | |
| fi | |
| } | |
| # Check that we're in a BASH shell | |
| if test -z "$BASH" ; then | |
| echo "update-hosts.sh must be run in the BASH shell... Aborting."; echo; | |
| exit 192 | |
| fi | |
| case $1 in | |
| add) | |
| isroot | |
| # Do we have enough arguments? | |
| if [ ! $# == 3 ]; then | |
| echo "Missing arguments: $0 add [host] [ip]"; echo; | |
| exit 192 | |
| fi | |
| # Does the host look valid? | |
| if [[ ! $2 =~ $DOMAINREGEX ]]; then | |
| echo "Invalid hostname: $2"; echo; | |
| exit 192 | |
| fi | |
| # Does the IP look valid? | |
| if [[ ! $3 =~ $IPREGEX ]]; then | |
| echo "Invalid IP address: $3"; echo; | |
| exit 192 | |
| fi | |
| # Check to see if the host is already in the file | |
| REGEX="$2$" | |
| if [ $(cat $HOSTSFILE | grep '$REGEX' | wc -l | sed 's/^ *//g') != 0 ]; then | |
| echo "The host $2 is already in the hosts file."; echo; | |
| exit 192 | |
| fi | |
| echo -e "$3\t$2" >> $HOSTSFILE | |
| echo "Added $2"; echo | |
| ;; | |
| check) | |
| # Do we have enough arguments? | |
| if [ ! $# == 2 ]; then | |
| echo "Missing arguments: $0 check [host]"; echo | |
| exit 192 | |
| fi | |
| REGEX="${2}$"; | |
| if [ $(cat $HOSTSFILE | grep $REGEX | wc -l | sed 's/^ *//g') != 0 ]; | |
| then | |
| cat $HOSTSFILE | grep $2 | |
| else | |
| echo "The host $2 was not found in the host file."; echo; | |
| fi | |
| ;; | |
| remove) | |
| isroot | |
| REGEX="$2$" | |
| if [ $(cat $HOSTSFILE | grep $REGEX | wc -l | sed 's/^ *//g') = 0 ]; then | |
| echo "The host $2 was not found in the host file."; echo; | |
| exit 0; | |
| fi | |
| backup | |
| cat $HOSTSFILE | sed -e "/$2$/ d" > tmp && mv tmp $HOSTSFILE | |
| echo "$2 entry removed."; echo | |
| ;; | |
| update) | |
| isroot | |
| # Does the IP look valid? | |
| if [[ ! $3 =~ $IPREGEX ]]; then | |
| echo "Invalid IP address: $3"; echo; | |
| exit 192 | |
| fi | |
| # Does the host look valid? | |
| if [[ ! $2 =~ $DOMAINREGEX ]]; then | |
| echo "Invalid hostname: $2"; echo; | |
| exit 192 | |
| fi | |
| backup | |
| $0 remove $2 | |
| $0 add $2 $3 | |
| echo "$2 entry updated to $3"; echo | |
| ;; | |
| rollback) | |
| isroot | |
| if [ -f $BAKFILE ] | |
| then | |
| cat $BAKFILE > $HOSTSFILE | |
| rm $BAKFILE | |
| echo "Rollback complete."; echo | |
| else | |
| echo "No backup file found!"; echo | |
| fi | |
| ;; | |
| -h) | |
| usage | |
| ;; | |
| *) | |
| echo "Missing command. Type $0 -h for usage."; echo | |
| ;; | |
| esac | |
| exit 0 |
Thank you very much. This is really helpful.
Thank you. Just what I needed.
Apparently, there is a dependency on Bash 3.2. Had to upgrade bash 2.0 on the server :)
Hi Mike,
Just found an issue with the script.
I've scheduled your script in cron:
*/15 * * * * root /usr/local/bin/etchosts.sh update ecc606-b dig +short a hostname1.xyz.com
Despite using update command, after couple of days my /etc/hosts file is full of identical records like:
54.194.xxx.xxx ecc606-b
54.194.xxx.xxx ecc606-b
54.194.xxx.xxx ecc606-b
54.194.xxx.xxx ecc606-b
54.194.xxx.xxx ecc606-b
54.194.xxx.xxx ecc606-b
54.194.xxx.xxx ecc606-b
54.171.yyy.yyy ecc606-b
54.171.yyy.yyy ecc606-b
54.171.yyy.yyy ecc606-b
54.171.yyy.yyy ecc606-b
54.171.yyy.yyy ecc606-b
54.171.yyy.yyy ecc606-b
I thought update should update the record, but not add a new one into the /etc/hosts file. Could you check please?
Dmitry
In playing around with this script I noticed that (at least for remove on OSX) the suffix of the hostname is matched. So, if you have bobworkstation and tomworkstation and remove tomworkstation, then you also lose the host entry for bobworkstation.
very useful, thank you!
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Thank you! Started using it!