bash - using a command line argument (hostname) to run an external command-CodePudding

First time post, please forgive any missing information.

I have a script that is supposed to work with icinga. I need icinga to log into my Linux box and run a command like "script ". The script will then run a command to that hostname like sudo /etc/init.d/apache2 status then report back "running or unused" and an exit status of 0 or 2. I'm wondering how I could add another command and have it one or the other run depending on what hostname it's given. Half of them need apache2 to be running and the other half need to have a process called dss to be running. I'd rather not have two separate scripts. Here is the working script and sorry it's sloppy but I haven't done any clean up and I'm not real good at bash yet.

so the user would run the script ./chkdss2 or

#!/bin/bash
ec=0
ec1=2
var3=run
var4=unused

for host in "$@"
do
  var1=`ssh $host sudo /etc/init.d/dss status|awk '{print $6}'`
  var2="$( echo $var1 | cut -c 3-5 )"
if [[ "$var2" == "$var3" ]]; then
    echo "$host is running"
    echo $ec
  else
    echo "$host is not running"
    echo $ec1
fi
done

CodePudding user response：

There are a couple ways to test if a particular hostname is for apache or dss. You only need to have a list of hostnames for each case, and check if the received hostnames are included in said lists.

Method 1: using arrays

#!/bin/bash

# Method 1, using array lists of hosts
apachehosts=('ap1' 'ap2' 'ap3')
dsshosts=('dss1' 'dss2' 'dss3')

for host in "$@"
do
    if printf '%s\n' "${apachehosts[@]}" | grep -Fxq "$host"
    then
        echo "$host: APACHE HOST"
    elif printf '%s\n' "${dsshosts[@]}" | grep -Fxq "$host"
    then
        echo "$host: DSS HOST"
    else
        echo "ERROR, $host: unknown host"
    fi
done

To modify the lists of hosts, simply add or remove values in the declaration of arrays apachehosts and dsshosts.

Method 2: using case

#!/bin/bash

# Method 2, using case
for host in "$@"
do
    case "$host" in
        'ap1'|'ap2'|'ap3')
            echo "CASE, $host: APACHE HOST"
            ;;
        'dss1'|'dss2'|'dss3')
            echo "CASE, $host: DSS HOST"
            ;;
        *)
            echo "ERROR CASE, $host: unknown host"
            ;;
    esac
done

Here, you edit the patterns in each case.

Method 3: using if

#!/bin/bash

# Method 3, using if
for host in "$@"
do
    if [[ "$host" == 'ap1' || "$host" == 'ap2' || "$host" == 'ap3' ]]
    then
        echo "IF, $host: APACHE HOST"
    elif [[ "$host" == 'dss1' || "$host" == 'dss2' || "$host" == 'dss3' ]]
    then
        echo "IF, $host: DSS HOST"
    else
        echo "IF, $host: unknown host"
    fi
done

Here you modify the if conditions. I prefer the other methods, since this one is more complicated to edit, it is not as clear, especially if your list of hosts is long.

Method 4: condition on the hostnames

If you are lucky, there is some pattern to your hostnames. Ex. all apache servers start with letters ap, all your dss servers include dss in the name, ...

You can then simply use 2 if statements to decide which is which.

#!/bin/bash

# Method 4, patterns
for host in "$@"
do
    if [[ $(echo "$host" | grep -c -e "^ap") -ne 0 ]]
    then
        echo "PATTERNS, $host: APACHE HOST"
    elif [[ $(echo "$host" | grep -c -e "dss") -ne 0 ]]
    then
        echo "PATTERNS, $host: DSS host"
    else
        echo "PATTERNS, $host: unknown host"
    fi
done

Note: hostname apdss1 would come out as an Apache server here. Previous methods would respond "unknown host". You patterns must be strict enough to avoid mismatches.

CodePudding user response：

I had a similar task to get few report items using single ssh request.

I had to retrieve in singel ssh command:

Full hostname (FQDN)
Linux version
IP address of its Docker host if exist, or "none"

I got my script to work in 3 stage.

1. Get multiple lines of information from remote host

ssh -q dudi-HP-Compaq-Elite-8300-MT  <<< '
date  %F:%T   # line 1: time stamp
hostname -f     # line 2: hostname 
awk  "/DESCR/{print \$3}" /etc/lsb-release # line 3 : host linux distribution version
ip a | awk "/inet / && !/127.0.0.1/{sub(\"/.*\",\"\",\$2);printf(\"%s \", \$2)}"      # line 4: list IP address to the host
'

Results:

2022-03-05:22:22:21
dudi-HP-Compaq-Elite-8300-MT
20
192.168.2.111 192.168.122.1 172.17.0.1

2. Process multiple lines of information from remote host

Read lines of information from remote host, into an array sshResultsArr.

readarray -t sshResultsArr < <(ssh -q dudi-HP-Compaq-Elite-8300-MT  <<< '
date  %F:%T   # line 1: time stamp
hostname -f     # line 2: hostname 
awk  "/DESCR/{print \$3}" /etc/lsb-release # line 3 : host linux distribution version
ip a | awk "/inet / && !/127.0.0.1/{sub(\"/.*\",\"\",\$2);printf(\"%s \", \$2)}"      # line 4: list IP address to the host
')
hostname=${sshResultsArr[1]}
osVersion=${sshResultsArr[2]}
hasDockerIp=$(grep -Eo "172(.[[:digit:]]{1,3}){3}" <<< "${sshResultsArr[3]}") # find IP starting with 172
hasDockerIp=${hasDockerIp:="none"} # if not found IP set to "NONE"

printf "%s \t OS version: %s \t has Docker IP: %s\n" "$hostname" "$osVersion" "$hasDockerIp"

Result:

dudi-HP-Compaq-Elite-8300-MT     OS version: 20          has Docker IP: 172.17.0.1

3. Process each remote host in a loop

#!/bin/bash
for host in "$@"; do
  readarray -t sshResultsArr < <(ssh -q $host  <<< '
  date  %F:%T   # line 1: time stamp
  hostname -f     # line 2: hostname 
  awk  "/DESCR/{print \$3}" /etc/lsb-release # line 3 : host linux distribution version
  ip a | awk "/inet / && !/127.0.0.1/{sub(\"/.*\",\"\",\$2);printf(\"%s \", \$2)}"      # line 4: list IP address to the host
  ')
  hostname=${sshResultsArr[1]}
  osVersion=${sshResultsArr[2]}
  hasDockerIp=$(grep -Eo "172(.[[:digit:]]{1,3}){3}" <<< "${sshResultsArr[3]}") # find IP starting with 172
  hasDockerIp=${hasDockerIp:="none"} # if not found IP set to "NONE"

  printf "%s \t OS version: %s \t has Docker IP: %s\n" "$hostname" "$osVersion" "$hasDockerIp"
done