Bash new variable with other variable - bash

I get the ip address like that :
Ip=`ifconfig | grep inet | grep -v -E 'inet6|127.0.0.1' | \
tr -d [:alpha:] | tr -s [:space:] | cut -d: -f2`
I have an ip like this for instance : 10.1.0.76
I want to make a new variable with the Ip variable to have another ip, for instance my new variable will return : 10.1.0.178
Just the last number change, so I want to get just a part of Ip variable (10.1.0.) and add another number to the end.
I tried with sed but I always have mistakes like "there's no file call'd ..."
Can you help me ?

You can use parameter expansion: It's simply: ${Ip%.*}.178
${Ip%.*} is the ip with the last dot and everything after it removed. The .178 is what you want to append after that.
Here it is in context:
# Your original expression
Ip=`ifconfig | grep inet | grep -v -E 'inet6|127.0.0.1' | \
tr -d [:alpha:] | tr -s [:space:] | cut -d: -f2`
# assign a new variable with the ip with different end octet
newIp=${Ip%.*}.178
# Show new ip
echo "$newIp"

Well, given that you have IP in a format x.y.z.w, you can use perl regex:
$ echo "120.20.31.78" | perl -pe 's/(.*)\..*/$1\.123/'
120.20.31.123
This will repace last number ("78") with "123".
So, in your case (assuming your "Ip" variable is set correctly), it would be:
Ip=ifconfig | grep inet | grep -v -E 'inet6|127.0.0.1' | tr -d [:alpha:] | tr -s [:space:] | cut -d: -f2 | perl -pe 's/(.*)\..*/$1\.123/'

see this, I hope it is what you want:
kent$ echo $ip
10.1.0.76
kent$ echo $part
178
kent$ sed -r "s/(.*\.).*/\1$part/" <<< $ip
10.1.0.178
to set $ip with new value:
kent$ ip=$(sed -r "s/(.*\.).*/\1$part/" <<< $ip)
kent$ echo $ip
10.1.0.178

Related

How to trim a string in shell script

I have a string,
var=refs/heads/testing/branch
I want to get rid of refs/heads/ in the string using shell script, such that I have only:
var=testing/branch
Commands I tried (one per line):
echo $(var) | awk -F\\ {'print $2'}
echo $var | sed -e s,refs/heads/,,
echo "refs/heads/testing/branch" | grep -oP '(?<=refs/heads/\)\w+'
echo "refs/heads/testing/branch" | LC_ALL=C sed -e 's/.*\\//'
echo "refs/heads/testing/branch" | cut -d'\' -f2
echo refs/heads/testing/branch | sed -e s,refs/heads/,,
there are lots of options out there ,try easy ones:
echo $var | cut -d "/" -f 3,4
echo $var | awk -F"/" '{print $3"/"$4}'
Shell parameter expansion: remove the prefix "refs/heads/" from the variable contents
$ var=refs/heads/testing/branch
$ echo "${var#refs/heads/}"
testing/branch

Check ip is present within file & update iptables bash script

I want to check that the ip is present within the ccd folder and push the ip route to the FORWARDING chain in the iptables. Im new to bash scripting and need a little help finishing this script.
client file in /etc/openvpn/ccd :
ifconfig-push 10.8.0.45 255.255.255.0
push 'route 10.10.0.45'
I need to grep 10.8.0.45 & 10.10.0.45
and push those routes in the iptables.
e.g
iptables -A FORWARD -s 10.8.0.45 -d 10.10.0.45 -j ACCEPT
client-connect /etc/openvpn/on_connect.sh
script I need help with 'grep' or 'awk'
static_ip= cat $CCD_DIR/$common_name | grep -w "ifconfig-push" | awk -F ' ' {'print $2'}
ip_destination=cat $CCD_DIR/$common_name | grep -w "push 'route" | awk -F ' ' {'print $3'} | tr -d "'"
#!/usr/bin/env bash
#
# Add iptables rules based on CCD client config.
#
CCD_DIR="/etc/openvpn/ccd"
RULE_COMMENT="FORWARD"$common_name
static_ip=cat $CCD_DIR/$common_name | grep -w "ifconfig-push" | awk -F ' ' {'print $2'}.
ip_destination=cat $CCD_DIR/$common_name | grep -w "push 'route" | awk -F ' ' {'print $3'} | tr -d "'"
if [ -f $CCD_DIR/$common_name ]; then
sudo iptables -A FORWARD -s $static_ip -d ip_destination -j ACCEPT
fi
exit 0
Edit: I think my usage of cat is wrong .
Try like this.
static_ip=$( cat $CCD_DIR | grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b" | grep -E '(^|\s)10.8.0.45($|\s)' )
ip_destination=$( cat $CCD_DIR | grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b" | grep -E '(^|\s)10.10.0.45($|\s)' )
So first you grep all IP's address in file and then you search exactly what you need
Edited after your comment.
If I understand correctly,
"ifconfig-push" - Is only one peer ccd file ?
so you can use this :
static_ip=$( grep -w "ifconfig-push" | awk -F ' ' {'print $2'})
For the rest in "push route" you need to use loop to find all matching ip address and put them to the iptables.
if [ -f $CCD_DIR/$common_name ]
then
cat $CCD_DIR | awk -F 'route' {'print $2'} | awk -F ' ' {'print $1'} | sed '/^$/d' | grep -E "\b(10)\.(8)\.(0)\.|(10)\.(10)\.(0).\b" | while read ip_destination
do
sudo iptables -A FORWARD -s $static_ip -d ip_destination -j ACCEPT
done
fi

Using sed to change ip addresses in dhcpcd.conf file

On a raspberry pi I am trying to write a simple script that will allow me to change the static ip settings in the dhcpcd.conf file. The below script works except for the dns-servers. It appears that the sed statement does not work for that line as it contains two ip addresses seperated by a space. The script is as follows:
#!/bin/bash
currip=$(cat /etc/dhcpcd.conf | grep -e '^static ip_address=' | cut -d= -
f2)
currgw=$(cat /etc/dhcpcd.conf | grep -e '^static routers=' | cut -d= -f2)
currdns=$(cat /etc/dhcpcd.conf | grep -e '^static domain_name_servers=' |
cut -d= -f2)
echo "current IP is $currip"
echo "current GW is $currgw"
echo "current DNS servers are $currdns"
echo "Enter new static ip in form of x.x.x.x/x: "
read newip
echo "Enter new GW in form of x.x.x.x: "
read newgw
echo "Enter new DNS servers in form of x.x.x.x x.x.x.x: "
read newdns
echo "currip is $currip"
echo "new ip will be $newip"
echo "new dns will be $newdns"
sed -i -e "s#$currip\b#$newip#g" /etc/dhcpcd.conf
sed -i -e "s#$currgw\b#$newgw#g" /etc/dhcpcd.conf
sed -i -e "s#$currdns\b#$newdns#g" /etc/dhcpcd.conf
chip=$(cat /etc/dhcpcd.conf | grep -e '^static ip_address=' | cut -d= -
f2)
chgw=$(cat /etc/dhcpcd.conf | grep -e '^static routers=' | cut -d= -f2)
chdns=$(cat /etc/dhcpcd.conf | grep -e '^static domain_name_servers=' |
cut -d= -f2)
echo "The ip has been changed to $chip"
echo "The GW has been changed to $chgw"
echo "The DNS server have been changed to $chdns"
The lines in the dhcpcd.conf file look like this:
static ip_address=192.168.126.7/24
static routers=192.168.126.1
static domain_name_servers=192.168.126.1 66.243.243.101
How do I need to tweak my sed statement for the domain_name_servers?
The problem is your static router "192.168.126.1" is also present in the static domain_name_servers. Therefore, when you overwrite the routers with
sed -i -e "s#$currgw\b#$newgw#g" /etc/dhcpcd.conf
the line in your conf file is changed to
static domain_name_servers={{what you entered}} 66.243.243.101
so it no longer it matched by the name servers sed.
I suggest changing the find and replace strings to include the keys as well as the values, such as in the following:
sed -i -e "s#^static ip_address=$currip\b#static ip_address=$newip#g" dhcpcd.conf
sed -i -e "s#^static routers=$currgw\b#static routers=$newgw#g" dhcpcd.conf
sed -i -e "s#^static domain_name_servers=$currdns\b#static domain_name_servers=$newdns#g" dhcpcd.conf**strong text**
This will make it so no other lines that happen to contain an earlier replaced-string will be changed

Pass value from output of one command to sed

I have a file, config.txt with many lines. One line is like this
address=
I am getting the ip address of the machine on which config.txt resides, with
ip addr | grep 'state UP' -A2 | tail -1 | awk '{print $2}' | cut -f1 -d'/'
That code is taken from a Stack Overflow answer.. The output I am getting is an IP address -
192.168.3.260
I would like to replace
address=
in config.txt with
address='192.168.3.260'
Is it possible to do it in one line, i.e.
ip addr | grep 'state UP' -A2 | tail -1 | awk '{print $2}' | cut -f1 -d'/' | <some sed command >
Using grep, cut and awk in a single pipeline is almost always a mistake, since awk can do everything grep can do, and then some. You can extract the IP address with a sed one-liner, like this:
ip addr | sed -n '/state UP/ {n;n;s/ *inet \(.*\)\/.*/\1/p}'
You can also use this approach to build the command you are looking for:
ip addr | sed -n "/state UP/ {n;n;s/ *inet \(.*\)\/.*/s|address=|\&'\1'|/p}"
which prints something like this:
s|address=|&'192.168.3.260'|
And then you can pipe that program to sed:
ip addr | sed -n "/state UP/ {n;n;s/ *inet \(.*\)\/.*/s|address=|\&'\1'|/p}" \
| sed -f - config.txt
sed -i 's/address=/address='$(ip addr | grep 'state UP' -A2 | tail -1 | awk '{print $2}' | cut -f1 -d'/')'/' filename
Where filename is the name of the file in question, the key here is to use indirection i.e. $(ip addr | grep 'state UP' -A2 | tail -1 | awk '{print $2}' | cut -f1 -d'/') and then use this in a sed command placing particular emphasis on the quotation marks. The indirection must side outside of the single quotation marks of the sed command.

how to parse a string in Shell script

I want to parse the following string in shell script.
VERSION=2.6.32.54-0.11.def
Here I want to get two value.
first = 263254
second = 11
I am using following to get the first value:
first=`expr substr $VERSION 1 9| sed "s/\.//g" |sed "s/\-//g"`
to get the second:
second=`expr substr $VERSION 10 6| sed "s/\.//g" |sed "s/\-//g"`
Using above code the output is:
first=263254
second=11
The result wont be consistent if version is changed to:
VERSION=2.6.32.54-0.1.def
Here second value will become 1d, but I want it give output of 1 only.
How can I directly parse the number after '-' and before '.d'?
$ first=$(echo $VERSION | cut -d- -f1 | sed 's/\.//g')
$ second=$(echo $VERSION | cut -d- -f2 | cut -d. -f2)
$ first=$(echo $VERSION | cut -d- -f1 | tr -d '.')
$ second=$(echo $VERSION | cut -d- -f2 | cut -d. -f2)
$ echo $first
263254
$ echo $second
11
you don't need multiple processes (sed|sed|sed...). single process with awk should work.
if you have VERSION=xxxx as string:
to get the first:
awk -F'[-=]' '{gsub(/\./,"",$2)}$0=$2'
to get the second:
awk -F'-|\\.def' '{split($2,a,".")}$0=a[2]'
test:
first:
kent$ echo "VERSION=2.6.32.54-0.1.def"|awk -F'[-=]' '{gsub(/\./,"",$2)}$0=$2'
263254
second
kent$ echo "VERSION=2.6.32.54-0.1.def"|awk -F'-|\\.def' '{split($2,a,".")}$0=a[2]'
1
kent$ echo "VERSION=2.6.32.54-0.1234.def"|awk -F'-|\\.def' '{split($2,a,".")}$0=a[2]'
1234
if you have VERSION=xxx as variable $VERSION:
first:
awk -F'-' '{gsub(/\./,"",$1)}$0=$1'
second:
awk -F'-|\\.def' '{split($2,a,".")}$0=a[2]'
test:
VERSION=2.6.32.54-0.1234.def
kent$ echo $VERSION|awk -F'-' '{gsub(/\./,"",$1)}$0=$1'
263254
7pLaptop 11:18:22 /tmp/test
kent$ echo $VERSION|awk -F'-|\\.def' '{split($2,a,".")}$0=a[2]'
1234
You should use regular expressions instead of the number of characters.
first=`sed 's/.//g' | sed 's/\(.*\)-.*/\1/'`
second=`sed 's/.//g' | sed 's/.*-\([0-9]*\).*/\1/'`
\(...\) are used to create a capturing group, and \1 output this group.
first=$(echo ${VERSION} | sed -e 's/^\([^-]*\)-0\.\([0-9]*\)\.def/\1/' -e 's/\.//g')
second=$(echo ${VERSION} | sed -e 's/^\([^-]*\)-0\.\([0-9]*\)\.def/\2/' -e 's/\.//g')
$ first=$(echo $VERSION | awk -F"\." '{gsub(/-.*/,"",$4);print $1$2$3$4}')
$ second=$(echo $VERSION | awk -F"\." '{print $5}' )

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