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Full Discussion: sed adding a blank line
Top Forums Shell Programming and Scripting sed adding a blank line Post 302554113 by bugeye on Saturday 10th of September 2011 04:55:59 AM
Old 09-10-2011
sed adding a blank line
I use the following as part of a script to correct for a faulty hostname file.

Code:
# get the domain name
read -r thehostname < /etc/hostname
dom="$(echo $thehostname | cut -d'.' -f2)"
numchar=${#dom}
if [ "$numchar" -le 5 ]
then
echo "It appears as though the hostname is not correctly set."
echo "Hostname has $thehostname as your hostname." 
echo "Please enter the domain name"
read realdom
dom=$realdom
thehostname="svr.$realdom.com"
sed -i 1c"$thehostname" /etc/hostname
fi

The code works fine, but it always adds a blank line at the end of the hostname file. (the extra is noticed by an additional byte as well as in notepad++.)

It does not appear to be a real problem, since it doesnt actually affect anything else. But I would like the script to be more precise and not add anything.

Am I using sed incorrectly? Is there a switch that would prevent it from adding the newline?
 

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LEARN ABOUT CENTOS

hostname

HOSTNAME(5)							     hostname							       HOSTNAME(5)

NAME

       hostname - Local hostname configuration file

SYNOPSIS

       /etc/hostname

DESCRIPTION

       The /etc/hostname file configures the name of the local system that is set during boot using the sethostname(2) system call. It should
       contain a single newline-terminated hostname string. The hostname may be a free-form string up to 64 characters in length; however, it is
       recommended that it consists only of 7-bit ASCII lower-case characters and no spaces or dots, and limits itself to the format allowed for
       DNS domain name labels, even though this is not a strict requirement.

       Depending on the operating system, other configuration files might be checked for configuration of the hostname as well, however only as
       fallback.

       You may use hostnamectl(1) to change the value of this file from the command line.

HISTORY

       The simple configuration file format of /etc/hostname originates from Debian GNU/Linux.

SEE ALSO

       systemd(1), sethostname(2), hostname(1), hostname(7), machine-id(5), machine-info(5), hostnamectl(1), systemd-hostnamed.service(8)

systemd 208															       HOSTNAME(5)
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