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Top Forums UNIX for Beginners Questions & Answers How to use cat grep and cut together? Post 303044564 by synack on Wednesday 26th of February 2020 12:56:31 PM
Old 02-26-2020
Quote:
Originally Posted by RudiC
There's NO string like "reached" in your samples, nor semicolons. Those don't show up in my host calls, either. Replace ! /^Host/ with /domain/ or /name/ or /pointer/. If that doesn't help, show your input data.


cat is by no means needed in any of your attempts as both grep and cut can open files by themselves, or you can redirect stdin for them.
grepping the first number is quite easy, like

Code:
$ host 82.165.230.17 | grep -o "^[^.]*"
17

, but extracting the remote hostname not so as you don't know what the FQDN looks like. The nearest I get is

Code:
$ host 82.165.230.17 | grep -oE "^[^.]*| [^. ]*\."
17
 bap.

Yes you are right. it's my fault. There somes lines that i didn't see in the original file, like ";; connection timed out; no servers could be reached"


thank you for your explanation and your help.
 

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HOSTNAME(1)						     Linux Programmer's Manual						       HOSTNAME(1)

NAME
hostname - show or set the system's host name domainname - show or set the system's NIS/YP domain name dnsdomainname - show the system's DNS domain name nodename - show or set the system's DECnet node name SYNOPSIS
hostname [-v] [-a] [--alias] [-d] [--domain] [-f] [--fqdn] [-i] [--ip-address] [--long] [-s] [--short] [-y] [-n] [--node] hostname [-v] [-F filename] [--file filename] [hostname] domainname [-v] [-F filename] [--file filename] [name] nodename [-v] [-F filename] [--file filename] [name] hostname [-v] [-h] [--help] [-V] [--version] dnsdomainname [-v] DESCRIPTION
Hostname is the program that is used to either set or display the current host, domain or node name of the system. These names are used by many of the networking programs to identify the machine. The domain name is also used by NIS/YP. GET NAME When called without any arguments, the program displays the current names: hostname will print the name of the system as returned by the gethostname(2) function. nodename will print the DECnet node name of the system as returned by the getnodename(2) function. dnsdomainname will print the domain part of the FQDN (Fully Qualified Domain Name). The complete FQDN of the system is returned with host- name --fqdn. The function gethostname(2) is used to get the hostname. Only when the hostname -s is called will gethostbyname(3) be called. The differ- ence in gethostname(2) and gethostbyname(3) is that gethostbyname(3) is network aware, so it consults /etc/nsswitch.conf and /etc/host.conf to decide whether to read information in /etc/sysconfig/network or /etc/hosts the hostname is also set when the network interface is brought up. SET NAME When called with one argument or with the --file option, the commands set the host name, the NIS/YP domain name or the node name. Note, that only the super-user can change the names. It is not possible to set the FQDN or the DNS domain name with the dnsdomainname command (see THE FQDN below). The host name is usually set once at system startup in /etc/rc.d/rc.inet1 or /etc/init.d/boot (normally by reading the contents of a file which contains the host name, e.g. /etc/hostname). THE FQDN You can't change the FQDN (as returned by hostname --fqdn) or the DNS domain name (as returned by dnsdomainname) with this command. The FQDN of the system is the name that the resolver(3) returns for the host name. Technically: The FQDN is the name gethostbyname(2) returns for the host name returned by gethostname(2). The DNS domain name is the part after the first dot. Therefore it depends on the configuration (usually in /etc/host.conf) how you can change it. Usually (if the hosts file is parsed before DNS or NIS) you can change it in /etc/hosts. OPTIONS
-a, --alias Display the alias name of the host (if used). -d, --domain Display the name of the DNS domain. Don't use the command domainname to get the DNS domain name because it will show the NIS domain name and not the DNS domain name. Use dnsdomainname instead. -F, --file filename Read the host name from the specified file. Comments (lines starting with a `#') are ignored. -f, --fqdn, --long Display the FQDN (Fully Qualified Domain Name). A FQDN consists of a short host name and the DNS domain name. Unless you are using bind or NIS for host lookups you can change the FQDN and the DNS domain name (which is part of the FQDN) in the /etc/hosts file. -h, --help Print a usage message and exit. -i, --ip-address Display the IP address(es) of the host. -n, --node Display the DECnet node name. If a parameter is given (or --file name ) the root can also set a new node name. -s, --short Display the short host name. This is the host name cut at the first dot. -V, --version Print version information on standard output and exit successfully. -v, --verbose Be verbose and tell what's going on. FILES
/etc/hosts AUTHOR
Peter Tobias, <tobias@et-inf.fho-emden.de> Bernd Eckenfels, <net-tools@lina.inka.de> (NIS and manpage). Steve Whitehouse, <SteveW@ACM.org> (DECnet support and manpage). net-tools 28 Jan 1996 HOSTNAME(1)
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