Find string2 when exist string1 in file

Question

I have a configuration file (from Nagios) with the following structure:

define service{
    use                     pruebaspre-service,srv-pnp
    host_name               server1.es
    servicegroups           pruebasdatasourcesoaspre-servicegroup,pruebaspre-servicegroup
    service_description     Estado DataSource - cfio  JUVEPoolDSPoolDS
    check_command           check_ds_oas!cfio!JUVEPoolDSPoolDS!/opt/oracle/ias10g/10.1.2!1!0
}


define service{
    use                     pruebaspre-service,srv-pnp
    host_name               server1.es
    servicegroups           pruebasdatasourcesoaspre-servicegroup,pruebaspre-servicegroup
    service_description     Estado DataSource - cfio  REMEPoolDS
    check_command           check_ds_oas!cfio!REMEPoolDS!/opt/oracle/ias10g/10.1.2!1!0
}


define service{
    use                     pruebaspre-service,srv-pnp
    host_name               server2.es
    servicegroups           pruebasdatasourcesoaspre-servicegroup,pruebaspre-servicegroup
    service_description     Estado DataSource - cfio  iris_usr_irisPoolDS
    check_command           check_ds_oas!cfio!iris_usr_irisPoolDS!/opt/oracle/ias10g/10.1.3!1!0
}


define service{
    use                     pruebaspre-service,srv-pnp
    host_name               server2.es
    servicegroups           pruebasdatasourcesoaspre-servicegroup,pruebaspre-servicegroup
    service_description     Estado DataSource - cfio  REMEPoolDS
    check_command           check_ds_oas!cfio!REMEPoolDS!/opt/oracle/ias10g/10.1.2!1!0
}

define service{
    use                     pruebaspre-service,srv-pnp
    host_name               server2.es
    servicegroups           pruebasdatasourcesoaspre-servicegroup,pruebaspre-servicegroup
    service_description     Estado DataSource - cfio  redt2_usr_redt2PoolDS
    check_command           check_ds_oas!cfio!redt2_usr_redt2PoolDS!/opt/oracle/ias10g/10.1.3!1!0
}

To register a new service in this file, I need to first find if the service exists, for this I must find that for a check_command the host_name is not registered.

For example, I want to register:

define service {
     use pre-service tests, srv-pnp
     host_name server1.es
     servicegroups testsdatasourcesoaspre-servicegroup, pre-servicegroup tests
     service_description DataSource Status - cfio REMEPoolDS
     check_command check_ds_oas! cfio! REMEPoolDS! /opt/oracle/ias10g/10.1.2! 1! 0
}

so in the file I should look for it does not exist.

I tried it with a while loop that reads the file and when it finds

check_command check_ds_oas! Cfio! REMEPoolDS! /Opt/oracle/ias10g/10.1.2! 1! 0

it looks for the next one not to be

host_name server1.es

V_NAGIOS_COMMAND=check_ds_oas!cfio!REMEPoolDS!/opt/oracle/ias10g/10.1.2!1!0
if [ `grep ${V_NAGIOS_COMMAND} --count $V_FILE_NAGIOS` -ge 1 ] ; then
    while read LINEA_CONFIG
    do
        V_DIRECTIVA=`echo $LINEA_CONFIG| awk '{print $1} '`
        V_VALOR_DIRECTIVA=`echo $LINEA_CONFIG| awk '{print $2} '`
        if [ $V_DIRECTIVA = check_command ]&&[ $V_VALOR_DIRECTIVA = $V_NAGIOS_COMMAND ]; then
            V_COMANDO_ENCONTRADO=1
        elif [ $V_DIRECTIVA = host_name ]&& [ $V_COMANDO_ENCONTRADO = 1 ] ; then
            if [ $V_VALOR_DIRECTIVA = $V_MAQUINA ] ; then
                ((V_EXISTEN_DATOS++))
                return 1
            else
                V_COMANDO_ENCONTRADO=0
            fi
        fi
    done < <(tac $V_FILE_NAGIOS| grep -vE "^#|^$")
fi

but it is very slow.

Change while read LINEA_CONFIG to while read V_DIRECTIVA V_VALOR_DIRECTIVA and remove the two awk lines, that will help a lot. — wurtel
– wurtel, Commented Jul 16, 2019 at 8:37

LL3 · Accepted Answer · 2019-07-16 11:01:12Z

If I understood well your requirements, this looks like a job that sed can do well thanks to its ability to delimit "sub-streams" within its input stream.

This should be POSIX:

sed -n "/^define service/,/^}/{/^[[:blank:]]\\{1,\}host_name[[:blank:]]\\{1,\\}${V_MAQUINA}/,/^}/{\\%^[[:blank:]]\\{1,\\}check_command[[:blank:]]\\{1,\\}${V_NAGIOS_COMMAND}%{p;q}}}" file

or, if you can do with GNU sed, for a bit less escaping in string:

sed -En "/^define service/,/^\\}/{/^[[:blank:]]+host_name[[:blank:]]+${V_MAQUINA}/,/^\\}/{\\%^[[:blank:]]+check_command[[:blank:]]+${V_NAGIOS_COMMAND}%{p;q}}}" file

Explained:

sed -En  # use Extended Regular Expressions, and don't print by default

# main `sed` script for entire stream
/^define service/,/^\\}/  # between 'define service' and '}'
{  # sub-stream: between specified 'host_name' and '}'
/^[[:blank:]]+host_name[[:blank:]]+${V_MAQUINA}/,/^\\}/
{  # look for specified 'check_command', using '%' because '/' can be in command
\\%^[[:blank:]]+check_command[[:blank:]]+${V_NAGIOS_COMMAND}%
{p;q}  # if found, print line and quit `sed`
}
}

This prints the check_command line if found within the file's "snippet" delimited by the regexps, or nothing at all if not found.

You can therefore just check for presence or absence of a returned string.

Don't check for exit status because sed exits 0 also when nothing is printed.

A few additional notes:

we need \\ to express one \ because we are inside shell's double-quotes
we use double-quotes to be able to use your shell's variables $V_MAQUINA and $V_NAGIOS_COMMAND
I chose % as regexp delimiter in last regexp, but you are free to choose any character that won't be present in your $V_NAGIOS_COMMAND variable

muru · Accepted Answer · 2019-07-16 11:08:39Z

In awk:

/^define service/{

    found_command=0
    found_host=0

    while (getline && $0 !~ "^}") {

        # test host
        if($1 == "host_name") {
            if ($2 == new_host) {
                found_host=1
            }else{
                next
            }
        }

        # test check_command
        if($1 == "check_command"){
            cmd = gensub(/^\s*check_command\s*/, "", 1)
            if (cmd == new_command) {
                found_command=1
            }else{
                next
            }
        }
    }

    if (found_command && found_host)
        exit 1
}

can be used like this:

new_host='...'
new_command='...'
if awk -v new_host="$new_host" -v new_command="$new_command" -f script.awk cfg_file ; then
    echo "you can register it now"
fi

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