11-15-2008
Delete Blank Lines Between DHCP Host Blocks
Hi All,
I have a dhcpd.conf file that gets static hosts added and removed via a shell script. After sometime, there becomes huge gaps of space ( blank lines ) between each host block. I tried a couple of sed one-liners; but, I can't seem to get the output I'm looking for. Also, I would like to delete the blank lines between the host blocks interactively instead of piping to a file then doing a move back to the original file. Below is the output I'm looking for:
old dhcpd.conf:
host example1 {
hardware ethernet 00:00:00:00:00:01;
fixed-address 192.168.135.2;
option subnet-mask 255.255.255.0;
option routers 192.168.135.1;
next-server 192.168.135.210;
filename "linux-install/pxelinux.0";
}
host example2 {
hardware ethernet 00:00:00:00:00:02;
fixed-address 192.168.135.3;
option subnet-mask 255.255.255.0;
option routers 192.168.135.1;
next-server 192.168.135.210;
filename "linux-install/pxelinux.0";
}
host example3 {
hardware ethernet 00:00:00:00:00:03;
fixed-address 192.168.135.4;
option subnet-mask 255.255.255.0;
option routers 192.168.135.1;
next-server 192.168.135.210;
filename "linux-install/pxelinux.0";
}
new dhcpd.conf file:
host example1 {
hardware ethernet 00:00:00:00:00:01;
fixed-address 192.168.135.2;
option subnet-mask 255.255.255.0;
option routers 192.168.135.1;
next-server 192.168.135.210;
filename "linux-install/pxelinux.0";
}
host example2 {
hardware ethernet 00:00:00:00:00:02;
fixed-address 192.168.135.3;
option subnet-mask 255.255.255.0;
option routers 192.168.135.1;
next-server 192.168.135.210;
filename "linux-install/pxelinux.0";
}
host example3 {
hardware ethernet 00:00:00:00:00:03;
fixed-address 192.168.135.4;
option subnet-mask 255.255.255.0;
option routers 192.168.135.1;
next-server 192.168.135.210;
filename "linux-install/pxelinux.0";
}
Any help would be greatly appreciated. Thanks in advance!
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
hi there
i'm trying to delete blank lines and or lines with spaces only from a series of files in an directory.
to do so, i'm using this:
for files in `ls /users/myname/pesop* 2>/dev/null`
do
grep -v ^$ $files > newfile
mv newfile $files
done
now, this works great for blank lines but... (3 Replies)
Discussion started by: vascobrito
3 Replies
2. Shell Programming and Scripting
I have a text file with blank lines fullfilled with spaces and others only containing the "Enter" caracter, the \012.
I would like to eliminate all them with the sed command.
Is it possible?
making: sed '/^$/d' <file should delete the blank lines but doesn't work for the lines that only... (2 Replies)
Discussion started by: tmxps
2 Replies
3. UNIX for Dummies Questions & Answers
can anyone show me how to delete blank lines from a file.
thanks in advance (2 Replies)
Discussion started by: sachin.gangadha
2 Replies
4. Shell Programming and Scripting
Hello,
Hello Firends,
I have file like below. I want to remove selected blocks say abc,pqr,lst. how can i remove those blocks from file.
zone abc {
blah
blah
blah }
zone xyz {
blah
blah
blah }
zone pqr {
blah
blah
blah } (4 Replies)
Discussion started by: nrbhole
4 Replies
5. UNIX for Dummies Questions & Answers
Hi,
I have blank line in the file, I just want to remove trailing blank lines.
There are some blank lines between the lines, i don't want remove those.
Just want to delete blank lines at the end.
I used this command sed '/^$/d' infile > outfile, but it is not removing anything.
I think... (1 Reply)
Discussion started by: visu
1 Replies
6. Shell Programming and Scripting
I have a sed pipeline:
myVar=$(cat $FILE | sed -n '/regex/,/regex/{/regex/d;p}' | sed -n '/regex/!p' | sed -e s/*:// | sed /regex/,+8d \
)
sed '/^$/d'
sed '/./!d'
And i've tried to add that in a different order rather then just on the end..Why isnt it deleting all the blank... (2 Replies)
Discussion started by: omgsomuchppl
2 Replies
7. Shell Programming and Scripting
Hi,
I want to use diff to compare two files in a Perl file. But one of the files has some blank lines at the end. So I want to delete the blank lines from the file firstly and then use diff to compare them. But I dont know how to delete the blank lines from the files. Meanwhile, the system is... (5 Replies)
Discussion started by: Damon_Qu
5 Replies
8. Shell Programming and Scripting
Hi,
Consider a file named "testfile"
The contents of file are as below
first line added for test
second line added for test
third line added for test
fourth line added for test
fifth line added for test (5 Replies)
Discussion started by: anil8103
5 Replies
9. UNIX for Advanced & Expert Users
Hi Gurus,
Somebody can say me how to delete blank spaces and blank lines in a file unix, please.
Thank you for advanced. (10 Replies)
Discussion started by: systemoper
10 Replies
10. UNIX for Beginners Questions & Answers
Hi all,
I'm looking for a way (sed or awk) to delete multiple lines between blank lines containing two patterns ex:
user: alpha
parameter_1 = 15
parameter_2 = 1
parameter_3 = 0
user: alpha
parameter_1 = 15
parameter_2 = 1
parameter_3 = 0
user: alpha
parameter_1 = 16... (3 Replies)
Discussion started by: ce9888
3 Replies
LEARN ABOUT FREEBSD
if_gre
GRE(4) BSD Kernel Interfaces Manual GRE(4)
NAME
gre -- encapsulating network device
SYNOPSIS
To compile the driver into the kernel, place the following line in the kernel configuration file:
device gre
Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):
if_gre_load="YES"
DESCRIPTION
The gre network interface pseudo device encapsulates datagrams into IP. These encapsulated datagrams are routed to a destination host, where
they are decapsulated and further routed to their final destination. The ``tunnel'' appears to the inner datagrams as one hop.
gre interfaces are dynamically created and destroyed with the ifconfig(8) create and destroy subcommands.
This driver corresponds to RFC 2784. Encapsulated datagrams are prepended an outer datagram and a GRE header. The GRE header specifies the
type of the encapsulated datagram and thus allows for tunneling other protocols than IP. GRE mode is also the default tunnel mode on Cisco
routers. gre also supports Cisco WCCP protocol, both version 1 and version 2.
The gre interfaces support a number of additional parameters to the ifconfig(8):
grekey Set the GRE key used for outgoing packets. A value of 0 disables the key option.
enable_csum Enables checksum calculation for outgoing packets.
enable_seq Enables use of sequence number field in the GRE header for outgoing packets.
EXAMPLES
192.168.1.* --- Router A -------tunnel-------- Router B --- 192.168.2.*
/
/
+------ the Internet ------+
Assuming router A has the (external) IP address A and the internal address 192.168.1.1, while router B has external address B and internal
address 192.168.2.1, the following commands will configure the tunnel:
On router A:
ifconfig greN create
ifconfig greN inet 192.168.1.1 192.168.2.1
ifconfig greN inet tunnel A B
route add -net 192.168.2 -netmask 255.255.255.0 192.168.2.1
On router B:
ifconfig greN create
ifconfig greN inet 192.168.2.1 192.168.1.1
ifconfig greN inet tunnel B A
route add -net 192.168.1 -netmask 255.255.255.0 192.168.1.1
NOTES
The MTU of gre interfaces is set to 1476 by default, to match the value used by Cisco routers. This may not be an optimal value, depending
on the link between the two tunnel endpoints. It can be adjusted via ifconfig(8).
For correct operation, the gre device needs a route to the decapsulating host that does not run over the tunnel, as this would be a loop.
The kernel must be set to forward datagrams by setting the net.inet.ip.forwarding sysctl(8) variable to non-zero.
SEE ALSO
gif(4), inet(4), ip(4), me(4), netintro(4), protocols(5), ifconfig(8), sysctl(8)
A description of GRE encapsulation can be found in RFC 2784 and RFC 2890.
AUTHORS
Andrey V. Elsukov <ae@FreeBSD.org>
Heiko W.Rupp <hwr@pilhuhn.de>
BUGS
The current implementation uses the key only for outgoing packets. Incoming packets with a different key or without a key will be treated as
if they would belong to this interface.
The sequence number field also used only for outgoing packets.
BSD
November 7, 2014 BSD