Check if service exists in bash (CentOS and Ubuntu)

To get the status of one service without "pinging" all other services, you can use the command:

systemctl list-units --full -all | grep -Fq "$SERVICENAME.service"

By the way, this is what is used in bash (auto-)completion (see in file /usr/share/bash-completion/bash_completion, look for _services):

COMPREPLY+=( $( systemctl list-units --full --all 2>/dev/null | \   awk '$1 ~ /\.service$/ { sub("\\.service$", "", $1); print $1 }' ) )

Or a more elaborate solution:

service_exists() {    local n=$1    if [[ $(systemctl list-units --all -t service --full --no-legend "$n.service" | sed 's/^\s*//g' | cut -f1 -d' ') == $n.service ]]; then        return 0    else        return 1    fi}if service_exists systemd-networkd; then    ...fi

Hope to help.

Rustam Mamat gets the credit for this:

If you list all your services, you can grep the results to see what's in there. E.g.:

# Restart apache2 service, if it exists.    if service --status-all | grep -Fq 'apache2'; then      sudo service apache2 restart    fi

On a SystemD system :

serviceName="Name of your service"if systemctl --all --type service | grep -q "$serviceName";then    echo "$serviceName exists."else    echo "$serviceName does NOT exist."fi

On a Upstart system :

serviceName="Name of your service"if initctl list | grep -q "$serviceName";then    echo "$serviceName exists."else    echo "$serviceName does NOT exist."fi

On a SysV (System V) system :

serviceName="Name of your service"if service --status-all | grep -q "$serviceName";then    echo "$serviceName exists."else    echo "$serviceName does NOT exist."fi