improving command error message info

go.mod

@@ -27,6 +27,7 @@ require (
 	github.com/kr/text v0.2.0 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/prometheus/client_model v0.3.0 // indirect
 	github.com/prometheus/procfs v0.9.0 // indirect
 	github.com/rogpeppe/go-internal v1.11.0 // indirect

go.sum

@@ -36,6 +36,8 @@ github.com/matttproud/golang_protobuf_extensions v1.0.4 h1:mmDVorXM7PCGKw94cs5zk
 github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f h1:KUppIJq7/+SVif2QVs3tOP0zanoHgBEVAwHxUSIzRqU=
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_golang v1.15.0 h1:5fCgGYogn0hFdhyhLbw7hEsWxufKtY9klyvdNfFlFhM=

zfs/pool.go

@@ -2,8 +2,11 @@ package zfs
 
 import (
 	"bufio"
+	"io"
 	"os/exec"
 	"strings"
+
+	"github.com/pkg/errors"
 )
 
 // PoolStatus enum contains status text
@@ -68,17 +71,23 @@ func poolNames() ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		return nil, err
+	}
 	scanner := bufio.NewScanner(out)
 
 	if err = cmd.Start(); err != nil {
-		return nil, err
+		return nil, errors.Wrapf(err, "Failed to start command %s", cmd.String())
 	}
 
 	for scanner.Scan() {
 		pools = append(pools, scanner.Text())
 	}
+
+	stde, _ := io.ReadAll(stderr)
 	if err = cmd.Wait(); err != nil {
-		return nil, err
+		return nil, errors.Wrapf(err, `Failed to wait command %s, err output: "%s"`, cmd.String(), string(stde))
 	}
 
 	return pools, nil