diff --git a/cmd/challengepool.go b/cmd/challengepool.go
index 18e8643e..b2ff36ef 100644
--- a/cmd/challengepool.go
+++ b/cmd/challengepool.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 	"os"
 
 	"github.com/0chain/gosdk/zboxcore/sdk"
@@ -42,16 +41,16 @@ var cpInfo = &cobra.Command{
 		doJSON, _ := cmd.Flags().GetBool("json")
 
 		if !flags.Changed("allocation") {
-			log.Fatal("missing required 'allocation' flag")
+			Fatal("missing required 'allocation' flag")
 		}
 
 		if allocID, err = flags.GetString("allocation"); err != nil {
-			log.Fatalf("can't get 'allocation' flag: %v", err)
+			Fatalf("can't get 'allocation' flag: %v", err)
 		}
 
 		var info *sdk.ChallengePoolInfo
 		if info, err = sdk.GetChallengePoolInfo(allocID); err != nil {
-			log.Fatalf("Failed to get challenge pool info: %v", err)
+			Fatalf("Failed to get challenge pool info: %v", err)
 		}
 		if doJSON {
 			util.PrintJSON(info)
diff --git a/cmd/common.go b/cmd/common.go
index dec31352..d1012cf7 100644
--- a/cmd/common.go
+++ b/cmd/common.go
@@ -95,7 +95,17 @@ func PrintError(v ...interface{}) {
 }
 
 func PrintInfo(v ...interface{}) {
-	fmt.Fprintln(os.Stdin, v...)
+	fmt.Fprintln(os.Stdout, v...)
+}
+
+func Fatal(v ...interface{}) {
+	fmt.Fprintln(os.Stderr, v...)
+	os.Exit(1)
+}
+
+func Fatalf(format string, v ...interface{}) {
+	fmt.Fprintf(os.Stderr, format, v...)
+	os.Exit(1)
 }
 
 func init() {
diff --git a/cmd/get_download_cost.go b/cmd/get_download_cost.go
index 2ea0f9dd..e69f5def 100644
--- a/cmd/get_download_cost.go
+++ b/cmd/get_download_cost.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/0chain/gosdk/core/common"
 	"github.com/0chain/gosdk/zboxcore/fileref"
@@ -17,7 +16,7 @@ func calculateDownloadCost(alloc *sdk.Allocation, fileSize int64, numBlocks int6
 	for _, d := range alloc.BlobberDetails {
 		readPrice, err := d.Terms.ReadPrice.ToToken()
 		if err != nil {
-			log.Fatalf("failed to convert %v to token, %v", d.Terms.ReadPrice, err)
+			Fatalf("failed to convert %v to token, %v", d.Terms.ReadPrice, err)
 		}
 
 		cost += sizeInGB(numBlocks*fileref.CHUNK_SIZE) * float64(readPrice)
@@ -26,14 +25,14 @@ func calculateDownloadCost(alloc *sdk.Allocation, fileSize int64, numBlocks int6
 
 	balance, err := common.ToBalance(cost)
 	if err != nil {
-		log.Fatalf("failed to convert %v to balance, %v", cost, err)
+		Fatalf("failed to convert %v to balance, %v", cost, err)
 	}
 	return balance
 }
 
 func downloadCost(alloc *sdk.Allocation, meta *sdk.ConsolidatedFileMeta, blocksPerMarker int) {
 	if meta.Type != fileref.FILE {
-		log.Fatal("not a file")
+		Fatal("not a file")
 	}
 
 	shardSize := (meta.ActualFileSize + int64(alloc.DataShards) - 1) / int64(alloc.DataShards)
@@ -61,18 +60,18 @@ var getDownloadCostCmd = &cobra.Command{
 		)
 
 		if !fflags.Changed("allocation") {
-			log.Fatal("missing required 'allocation' flag")
+			Fatal("missing required 'allocation' flag")
 		}
 
 		allocID = cmd.Flag("allocation").Value.String()
 		blocksPerMarker, err := cmd.Flags().GetInt("blocks-per-marker")
 
 		if err != nil {
-			log.Fatal("invalid blocks-per-marker value: ", err)
+			Fatal("invalid blocks-per-marker value: ", err)
 		}
 
 		if blocksPerMarker <= 0 {
-			log.Fatal("blocks-per-marker value cannot be <= 0")
+			Fatal("blocks-per-marker value cannot be <= 0")
 		}
 
 		var (
@@ -83,24 +82,24 @@ var getDownloadCostCmd = &cobra.Command{
 
 		if fflags.Changed("remotepath") {
 			if remotePath, err = fflags.GetString("remotepath"); err != nil {
-				log.Fatal("invalid 'remotepath' flag: ", err)
+				Fatal("invalid 'remotepath' flag: ", err)
 			}
 		}
 
 		if fflags.Changed("authticket") {
 			if authTicket, err = fflags.GetString("authticket"); err != nil {
-				log.Fatal("invalid 'authticket' flag: ", err)
+				Fatal("invalid 'authticket' flag: ", err)
 			}
 		}
 
 		if fflags.Changed("lookuphash") {
 			if lookupHash, err = fflags.GetString("lookuphash"); err != nil {
-				log.Fatal("invalid 'lookuphash' flag: ", err)
+				Fatal("invalid 'lookuphash' flag: ", err)
 			}
 		}
 
 		if remotePath == "" && authTicket == "" {
-			log.Fatal("'remotepath' or 'authticket' flag required")
+			Fatal("'remotepath' or 'authticket' flag required")
 		}
 
 		var (
@@ -113,11 +112,11 @@ var getDownloadCostCmd = &cobra.Command{
 			// by remote path
 
 			if alloc, err = sdk.GetAllocation(allocID); err != nil {
-				log.Fatal("fetching the allocation: ", err)
+				Fatal("fetching the allocation: ", err)
 			}
 
 			if meta, err = alloc.GetFileMeta(remotePath); err != nil {
-				log.Fatal("can't get file meta: ", err)
+				Fatal("can't get file meta: ", err)
 			}
 
 			downloadCost(alloc, meta, blocksPerMarker)
@@ -128,19 +127,19 @@ var getDownloadCostCmd = &cobra.Command{
 
 		alloc, err = sdk.GetAllocationFromAuthTicket(authTicket)
 		if err != nil {
-			log.Fatal("can't get allocation object: ", err)
+			Fatal("can't get allocation object: ", err)
 		}
 		var at = sdk.InitAuthTicket(authTicket)
 
 		if lookupHash == "" {
 			if lookupHash, err = at.GetLookupHash(); err != nil {
-				log.Fatal("can't get lookup hash from auth ticket: ", err)
+				Fatal("can't get lookup hash from auth ticket: ", err)
 			}
 		}
 
 		meta, err = alloc.GetFileMetaFromAuthTicket(authTicket, lookupHash)
 		if err != nil {
-			log.Fatal("can't get file meta: ", err)
+			Fatal("can't get file meta: ", err)
 		}
 
 		downloadCost(alloc, meta, blocksPerMarker)
diff --git a/cmd/get_upload_cost.go b/cmd/get_upload_cost.go
index 2be1f9a0..84acc36f 100644
--- a/cmd/get_upload_cost.go
+++ b/cmd/get_upload_cost.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"time"
 
@@ -28,7 +27,7 @@ var getUploadCostCmd = &cobra.Command{
 		)
 
 		if !fflags.Changed("allocation") {
-			log.Fatal("missing required 'allocation' flag")
+			Fatal("missing required 'allocation' flag")
 		}
 
 		allocID = cmd.Flag("allocation").Value.String()
@@ -36,39 +35,39 @@ var getUploadCostCmd = &cobra.Command{
 		var localPath string
 
 		if !fflags.Changed("localpath") {
-			log.Fatal("missing requried 'localpath' flag")
+			Fatal("missing requried 'localpath' flag")
 		}
 
 		if localPath, err = fflags.GetString("localpath"); err != nil {
-			log.Fatal("invalid 'localpath' flag: ", err)
+			Fatal("invalid 'localpath' flag: ", err)
 		}
 
 		if localPath == "" {
-			log.Fatal("empty local path")
+			Fatal("empty local path")
 		}
 
 		var fi os.FileInfo
 		if fi, err = os.Stat(localPath); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		if !fi.Mode().IsRegular() {
-			log.Fatal("not a regular file")
+			Fatal("not a regular file")
 		}
 
 		if duration, err = fflags.GetDuration("duration"); err != nil {
-			log.Fatal("invalid 'duration' flag:", err)
+			Fatal("invalid 'duration' flag:", err)
 		} else if duration < 0 {
-			log.Fatal("negative duration not allowed: ", duration)
+			Fatal("negative duration not allowed: ", duration)
 		}
 
 		if end, err = fflags.GetBool("end"); err != nil {
-			log.Fatal("invalid 'end' flag:", err)
+			Fatal("invalid 'end' flag:", err)
 		}
 
 		var alloc *sdk.Allocation
 		if alloc, err = sdk.GetAllocation(allocID); err != nil {
-			log.Fatal("fetching the allocation: ", err)
+			Fatal("fetching the allocation: ", err)
 		}
 
 		// until allocation ends
diff --git a/cmd/getallocation.go b/cmd/getallocation.go
index 2431b665..7e92e660 100644
--- a/cmd/getallocation.go
+++ b/cmd/getallocation.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 	"os"
 
 	"github.com/0chain/gosdk/core/common"
@@ -32,7 +31,7 @@ var getallocationCmd = &cobra.Command{
 		alloc, err := sdk.GetAllocation(allocationID)
 		if err != nil {
 			logger.Logger.Error("Error fetching the allocation", err)
-			log.Fatal("Error fetching/verifying the allocation")
+			Fatal("Error fetching/verifying the allocation")
 		}
 		if doJSON {
 			util.PrintJSON(alloc)
@@ -53,11 +52,11 @@ var getallocationCmd = &cobra.Command{
 
 		blocksPerMarker, err := cmd.Flags().GetInt("blocks-per-marker")
 		if err != nil {
-			log.Fatal("invalid blocks-per-marker. Error: ", err)
+			Fatal("invalid blocks-per-marker. Error: ", err)
 		}
 
 		if blocksPerMarker <= 0 {
-			log.Fatal("invalid blocks-per-marker. Should be greater than 0")
+			Fatal("invalid blocks-per-marker. Should be greater than 0")
 		}
 
 		fmt.Println("allocation:")
diff --git a/cmd/getmpt.go b/cmd/getmpt.go
index 1799e442..1aaa59bf 100644
--- a/cmd/getmpt.go
+++ b/cmd/getmpt.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"log"
 	"strings"
 
 	"github.com/0chain/gosdk/zboxcore/sdk"
@@ -19,18 +18,18 @@ var getMptKeyCommand = &cobra.Command{
 	Hidden: true,
 	Run: func(cmd *cobra.Command, args []string) {
 		if cmd.Flags().Changed("key") == false {
-			log.Fatal("Required Mpt key missing\n")
+			Fatal("Required Mpt key missing\n")
 		}
 		key := cmd.Flag("key").Value.String()
 		jsonBytes, err := sdk.GetMptData(key)
 		if err != nil {
-			log.Fatalf("Failed to get Mpt key: %v\n", err)
+			Fatalf("Failed to get Mpt key: %v\n", err)
 		}
 
 		var indented bytes.Buffer
 		err = json.Indent(&indented, jsonBytes, "", "\t")
 		if err != nil {
-			log.Fatalf("Result %s baddly formated: %v\n", string(jsonBytes), err)
+			Fatalf("Result %s baddly formated: %v\n", string(jsonBytes), err)
 		}
 
 		noBackSlash := strings.Replace(indented.String(), "\\", "", -1)
diff --git a/cmd/rename.go b/cmd/rename.go
index 3822a4af..229a703a 100644
--- a/cmd/rename.go
+++ b/cmd/rename.go
@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"fmt"
 	"os"
 
 	"github.com/0chain/gosdk/constants"
@@ -41,7 +40,7 @@ var renameCmd = &cobra.Command{
 		destName := cmd.Flag("destname").Value.String()
 		oldName := pathutil.Dir(remotePath)
 		if oldName == destName {
-			fmt.Println(remotePath + " renamed")
+			PrintInfo(remotePath + " renamed")
 			return
 		}
 
@@ -56,7 +55,7 @@ var renameCmd = &cobra.Command{
 			PrintError("Rename failed.", err)
 			os.Exit(1)
 		}
-		fmt.Println(remotePath + " renamed")
+		PrintInfo(remotePath + " renamed")
 	},
 }
 
diff --git a/cmd/stakepool.go b/cmd/stakepool.go
index a6558364..af0d0f35 100644
--- a/cmd/stakepool.go
+++ b/cmd/stakepool.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/0chain/gosdk/zboxcore/sdk"
 	"github.com/0chain/gosdk/zcncore"
@@ -81,31 +80,31 @@ var spInfo = &cobra.Command{
 
 		if flags.Changed("blobber_id") {
 			if providerID, err = flags.GetString("blobber_id"); err != nil {
-				log.Fatalf("Error: cannot get the value of blobber_id")
+				Fatalf("Error: cannot get the value of blobber_id")
 			} else {
 				providerType = sdk.ProviderBlobber
 			}
 		} else if flags.Changed("validator_id") {
 			if providerID, err = flags.GetString("validator_id"); err != nil {
-				log.Fatalf("Error: cannot get the value of validator_id")
+				Fatalf("Error: cannot get the value of validator_id")
 			} else {
 				providerType = sdk.ProviderValidator
 			}
 		} else if flags.Changed("authorizer_id") {
 			if providerID, err = flags.GetString("authorizer_id"); err != nil {
-				log.Fatalf("Error: cannot get the value of authorizer_id")
+				Fatalf("Error: cannot get the value of authorizer_id")
 			} else {
 				providerType = sdk.ProviderAuthorizer
 			}
 		}
 
 		if providerType == 0 || providerID == "" {
-			log.Fatal("Error: missing flag: one of 'blobber_id','validator_id' or authorizer_id is required")
+			Fatal("Error: missing flag: one of 'blobber_id','validator_id' or authorizer_id is required")
 		}
 
 		var info *sdk.StakePoolInfo
 		if info, err = sdk.GetStakePoolInfo(providerType, providerID); err != nil {
-			log.Fatalf("Failed to get stake pool info: %v", err)
+			Fatalf("Failed to get stake pool info: %v", err)
 		}
 		if doJSON {
 			util.PrintJSON(info)
@@ -136,30 +135,30 @@ var spUserInfo = &cobra.Command{
 
 		if flags.Changed("client_id") {
 			if clientID, err = flags.GetString("client_id"); err != nil {
-				log.Fatalf("can't get 'client_id' flag: %v", err)
+				Fatalf("can't get 'client_id' flag: %v", err)
 			}
 		}
 
 		limit, err = flags.GetInt("limit")
 		if err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		offset, err = flags.GetInt("offset")
 		if err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		if flags.Changed("all") {
 			isAll, err = flags.GetBool("all")
 			if err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 		}
 
 		if !isAll {
 			if _, err := getAndPrintStakePool(clientID, doJSON, offset, limit); err != nil {
-				log.Fatalf("Failed to get stake pool info: %v", err)
+				Fatalf("Failed to get stake pool info: %v", err)
 			}
 			return
 		}
@@ -167,7 +166,7 @@ var spUserInfo = &cobra.Command{
 		for curOff := offset; ; curOff += limit {
 			l, err := getAndPrintStakePool(clientID, doJSON, curOff, limit)
 			if err != nil {
-				log.Fatalf("Failed to get stake pool info: %v", err)
+				Fatalf("Failed to get stake pool info: %v", err)
 			}
 			if l == 0 {
 				return
@@ -210,53 +209,53 @@ var spLock = &cobra.Command{
 
 		if flags.Changed("miner_id") {
 			if providerID, err = flags.GetString("miner_id"); err != nil {
-				log.Fatalf("invalid 'miner_id' flag: %v", err)
+				Fatalf("invalid 'miner_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderMiner
 			}
 		} else if flags.Changed("sharder_id") {
 			if providerID, err = flags.GetString("sharder_id"); err != nil {
-				log.Fatalf("invalid 'sharder_id' flag: %v", err)
+				Fatalf("invalid 'sharder_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderSharder
 			}
 		} else if flags.Changed("blobber_id") {
 			if providerID, err = flags.GetString("blobber_id"); err != nil {
-				log.Fatalf("invalid 'blobber_id' flag: %v", err)
+				Fatalf("invalid 'blobber_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderBlobber
 			}
 		} else if flags.Changed("validator_id") {
 			if providerID, err = flags.GetString("validator_id"); err != nil {
-				log.Fatalf("invalid 'validator_id' flag: %v", err)
+				Fatalf("invalid 'validator_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderValidator
 			}
 		} else if flags.Changed("authorizer_id") {
 			if providerID, err = flags.GetString("authorizer_id"); err != nil {
-				log.Fatalf("invalid 'authorizer_id' flag: %v", err)
+				Fatalf("invalid 'authorizer_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderAuthorizer
 			}
 		} else if providerType == 0 || providerID == "" {
-			log.Fatal("missing flag: one of 'miner_id', 'sharder_id', 'blobber_id', 'validator_id', 'authorizer_id' is required")
+			Fatal("missing flag: one of 'miner_id', 'sharder_id', 'blobber_id', 'validator_id', 'authorizer_id' is required")
 		}
 
 		if !flags.Changed("tokens") {
-			log.Fatal("missing required 'tokens' flag")
+			Fatal("missing required 'tokens' flag")
 		}
 
 		if tokens, err = flags.GetFloat64("tokens"); err != nil {
-			log.Fatal("invalid 'tokens' flag: ", err)
+			Fatal("invalid 'tokens' flag: ", err)
 		}
 
 		if tokens < 0 {
-			log.Fatal("invalid token amount: negative")
+			Fatal("invalid token amount: negative")
 		}
 
 		if flags.Changed("fee") {
 			if fee, err = flags.GetFloat64("fee"); err != nil {
-				log.Fatal("invalid 'fee' flag: ", err)
+				Fatal("invalid 'fee' flag: ", err)
 			}
 		}
 
@@ -264,7 +263,7 @@ var spLock = &cobra.Command{
 		hash, _, err = sdk.StakePoolLock(providerType, providerID,
 			zcncore.ConvertToValue(tokens), zcncore.ConvertToValue(fee))
 		if err != nil {
-			log.Fatalf("Failed to lock tokens in stake pool: %v", err)
+			Fatalf("Failed to lock tokens in stake pool: %v", err)
 		}
 		fmt.Println("tokens locked, txn hash:", hash)
 	},
@@ -288,37 +287,37 @@ var spUnlock = &cobra.Command{
 
 		if flags.Changed("blobber_id") {
 			if providerID, err = flags.GetString("blobber_id"); err != nil {
-				log.Fatalf("invalid 'blobber_id' flag: %v", err)
+				Fatalf("invalid 'blobber_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderBlobber
 			}
 		} else if flags.Changed("validator_id") {
 			if providerID, err = flags.GetString("validator_id"); err != nil {
-				log.Fatalf("invalid 'validator_id' flag: %v", err)
+				Fatalf("invalid 'validator_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderValidator
 			}
 		} else if flags.Changed("authorizer_id") {
 			if providerID, err = flags.GetString("authorizer_id"); err != nil {
-				log.Fatalf("invalid 'authorizer_id' flag: %v", err)
+				Fatalf("invalid 'authorizer_id' flag: %v", err)
 			} else {
 				providerType = sdk.ProviderAuthorizer
 			}
 		}
 
 		if providerType == 0 || providerID == "" {
-			log.Fatal("missing flag: one of 'blobber_id','validator_id' or authorizer_id is required")
+			Fatal("missing flag: one of 'blobber_id','validator_id' or authorizer_id is required")
 		}
 
 		if flags.Changed("fee") {
 			if fee, err = flags.GetFloat64("fee"); err != nil {
-				log.Fatal("invalid 'fee' flag: ", err)
+				Fatal("invalid 'fee' flag: ", err)
 			}
 		}
 
 		unlocked, _, err := sdk.StakePoolUnlock(providerType, providerID, clientWallet.ClientID, zcncore.ConvertToValue(fee))
 		if err != nil {
-			log.Fatalf("Failed to unlock tokens in stake pool: %v", err)
+			Fatalf("Failed to unlock tokens in stake pool: %v", err)
 		}
 
 		// success
diff --git a/cmd/storage.go b/cmd/storage.go
index 99944270..5b618d63 100644
--- a/cmd/storage.go
+++ b/cmd/storage.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 	"time"
 
 	"github.com/0chain/gosdk/core/transaction"
@@ -27,7 +26,7 @@ var scConfig = &cobra.Command{
 
 		var conf, err = transaction.GetConfig("storage_sc_config")
 		if err != nil {
-			log.Fatalf("Failed to get storage SC configurations: %v", err)
+			Fatalf("Failed to get storage SC configurations: %v", err)
 		}
 		if doJSON {
 			util.PrintJSON(conf)
@@ -70,7 +69,7 @@ var lsBlobers = &cobra.Command{
 		doAll, _ := cmd.Flags().GetBool("all")
 		isStakable, err := cmd.Flags().GetBool("stakable")
 		if err != nil {
-			log.Fatalf("err parsing in stakable flag: %v", err)
+			Fatalf("err parsing in stakable flag: %v", err)
 		}
 		// set is_active=true to get only active blobbers
 		isActive := true
@@ -79,7 +78,7 @@ var lsBlobers = &cobra.Command{
 		}
 		list, err := sdk.GetBlobbers(isActive, isStakable)
 		if err != nil {
-			log.Fatalf("Failed to get blobbers: %v", err)
+			Fatalf("Failed to get blobbers: %v", err)
 		}
 
 		if doJSON {
@@ -107,21 +106,21 @@ var blobberInfoCmd = &cobra.Command{
 
 		if flags.Changed("json") {
 			if json, err = flags.GetBool("json"); err != nil {
-				log.Fatal("invalid 'json' flag: ", err)
+				Fatal("invalid 'json' flag: ", err)
 			}
 		}
 
 		if !flags.Changed("blobber_id") {
-			log.Fatal("missing required 'blobber_id' flag")
+			Fatal("missing required 'blobber_id' flag")
 		}
 
 		if blobberID, err = flags.GetString("blobber_id"); err != nil {
-			log.Fatal("error in 'blobber_id' flag: ", err)
+			Fatal("error in 'blobber_id' flag: ", err)
 		}
 
 		var blob *sdk.Blobber
 		if blob, err = sdk.GetBlobber(blobberID); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		if json {
@@ -166,15 +165,15 @@ var blobberUpdateCmd = &cobra.Command{
 		)
 
 		if !flags.Changed("blobber_id") {
-			log.Fatal("missing required 'blobber_id' flag")
+			Fatal("missing required 'blobber_id' flag")
 		}
 
 		if blobberID, err = flags.GetString("blobber_id"); err != nil {
-			log.Fatal("error in 'blobber_id' flag: ", err)
+			Fatal("error in 'blobber_id' flag: ", err)
 		}
 
 		if _, err = sdk.GetBlobber(blobberID); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		updateBlobber := new(sdk.UpdateBlobber)
@@ -182,7 +181,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("capacity") {
 			var capacity int64
 			if capacity, err = flags.GetInt64("capacity"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 
 			changedCapacity := common.Size(capacity)
@@ -192,7 +191,7 @@ var blobberUpdateCmd = &cobra.Command{
 		var delegateWallet string
 		if flags.Changed("delegate_wallet") {
 			if delegateWallet, err = flags.GetString("delegate_wallet"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateBlobber.DelegateWallet = &delegateWallet
 		}
@@ -200,7 +199,7 @@ var blobberUpdateCmd = &cobra.Command{
 		var storageVersion int
 		if flags.Changed("storage_version") {
 			if storageVersion, err = flags.GetInt("storage_version"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateBlobber.StorageVersion = &storageVersion
 		}
@@ -210,11 +209,11 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("read_price") {
 			var rp float64
 			if rp, err = flags.GetFloat64("read_price"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			readPriceBalance, err := common.ToBalance(rp)
 			if err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			terms.ReadPrice = &readPriceBalance
 			termsChanged = true
@@ -223,11 +222,11 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("write_price") {
 			var wp float64
 			if wp, err = flags.GetFloat64("write_price"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			writePriceBalance, err := common.ToBalance(wp)
 			if err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			terms.WritePrice = &writePriceBalance
 			termsChanged = true
@@ -236,7 +235,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("max_offer_duration") {
 			var mod time.Duration
 			if mod, err = flags.GetDuration("max_offer_duration"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			terms.MaxOfferDuration = &mod
 		}
@@ -246,7 +245,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("num_delegates") {
 			var nd int
 			if nd, err = flags.GetInt("num_delegates"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			stakePoolSettings.NumDelegates = &nd
 			stakePoolSettingChanged = true
@@ -255,7 +254,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("delegate_wallet") {
 			var dw string
 			if dw, err = flags.GetString("delegate_wallet"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			stakePoolSettings.DelegateWallet = &dw
 			stakePoolSettingChanged = true
@@ -264,7 +263,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("managing_wallet") {
 			var mw string
 			if mw, err = flags.GetString("managing_wallet"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateBlobber.ManagingWallet = &mw
 		}
@@ -272,7 +271,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("service_charge") {
 			var sc float64
 			if sc, err = flags.GetFloat64("service_charge"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			stakePoolSettings.ServiceCharge = &sc
 			stakePoolSettingChanged = true
@@ -281,7 +280,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("url") {
 			var url string
 			if url, err = flags.GetString("url"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateBlobber.BaseURL = &url
 		}
@@ -289,7 +288,7 @@ var blobberUpdateCmd = &cobra.Command{
 		if flags.Changed("not_available") {
 			var na bool
 			if na, err = flags.GetBool("not_available"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			if !na {
 				na = false
@@ -301,7 +300,7 @@ var blobberUpdateCmd = &cobra.Command{
 			var ia bool
 			// Check if the flag is set to true
 			if ia, err = flags.GetBool("is_restricted"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			if !ia {
 				ia = false
@@ -318,7 +317,7 @@ var blobberUpdateCmd = &cobra.Command{
 		}
 
 		if _, _, err = sdk.UpdateBlobberSettings(updateBlobber); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 		fmt.Println("blobber settings updated successfully")
 	},
@@ -343,38 +342,38 @@ var resetBlobberStatsCmd = &cobra.Command{
 		)
 
 		if !flags.Changed("blobber_id") {
-			log.Fatal("missing required 'blobber_id' flag")
+			Fatal("missing required 'blobber_id' flag")
 		}
 		if blobberID, err = flags.GetString("blobber_id"); err != nil {
-			log.Fatal("error in 'blobber_id' flag: ", err)
+			Fatal("error in 'blobber_id' flag: ", err)
 		}
 
 		if !flags.Changed("prev_allocated") {
-			log.Fatal("missing required 'prev_allocated' flag")
+			Fatal("missing required 'prev_allocated' flag")
 		}
 		if prevAllocated, err = flags.GetInt64("prev_allocated"); err != nil {
-			log.Fatal("error in 'prev_allocated' flag: ", err)
+			Fatal("error in 'prev_allocated' flag: ", err)
 		}
 
 		if !flags.Changed("prev_saved_data") {
-			log.Fatal("missing required 'prev_saved_data' flag")
+			Fatal("missing required 'prev_saved_data' flag")
 		}
 		if prevSavedData, err = flags.GetInt64("prev_saved_data"); err != nil {
-			log.Fatal("error in 'prev_saved_data' flag: ", err)
+			Fatal("error in 'prev_saved_data' flag: ", err)
 		}
 
 		if !flags.Changed("new_allocated") {
-			log.Fatal("missing required 'new_allocated' flag")
+			Fatal("missing required 'new_allocated' flag")
 		}
 		if newAllocated, err = flags.GetInt64("new_allocated"); err != nil {
-			log.Fatal("error in 'new_allocated' flag: ", err)
+			Fatal("error in 'new_allocated' flag: ", err)
 		}
 
 		if !flags.Changed("new_saved_data") {
-			log.Fatal("missing required 'new_saved_data' flag")
+			Fatal("missing required 'new_saved_data' flag")
 		}
 		if newSavedData, err = flags.GetInt64("new_saved_data"); err != nil {
-			log.Fatal("error in 'new_saved_data' flag: ", err)
+			Fatal("error in 'new_saved_data' flag: ", err)
 		}
 
 		resetBlobberStatsDto := &sdk.ResetBlobberStatsDto{
@@ -388,7 +387,7 @@ var resetBlobberStatsCmd = &cobra.Command{
 
 		_, _, err = sdk.ResetBlobberStats(resetBlobberStatsDto)
 		if err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 		fmt.Println("reset blobber stats successfully")
 	},
@@ -408,10 +407,10 @@ var resetVersionCmd = &cobra.Command{
 		)
 
 		if !flags.Changed("blobber_id") {
-			log.Fatal("missing required 'blobber_id' flag")
+			Fatal("missing required 'blobber_id' flag")
 		}
 		if blobberID, err = flags.GetString("blobber_id"); err != nil {
-			log.Fatal("error in 'blobber_id' flag: ", err)
+			Fatal("error in 'blobber_id' flag: ", err)
 		}
 
 		snv := sdk.StorageNodeIdField{
@@ -420,7 +419,7 @@ var resetVersionCmd = &cobra.Command{
 
 		_, _, err = sdk.ResetBlobberVersion(&snv)
 		if err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 		fmt.Println("reset blobber version successfully")
 	},
@@ -440,10 +439,10 @@ var insertKilledProviderId = &cobra.Command{
 		)
 
 		if !flags.Changed("id") {
-			log.Fatal("missing required 'blobber_id' flag")
+			Fatal("missing required 'blobber_id' flag")
 		}
 		if blobberID, err = flags.GetString("id"); err != nil {
-			log.Fatal("error in 'id' flag: ", err)
+			Fatal("error in 'id' flag: ", err)
 		}
 
 		snv := sdk.StorageNodeIdField{
@@ -452,7 +451,7 @@ var insertKilledProviderId = &cobra.Command{
 
 		_, _, err = sdk.InsertKilledProviderID(&snv)
 		if err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 		fmt.Println("insert killed id successfully")
 	},
diff --git a/cmd/validator.go b/cmd/validator.go
index 167ed389..677adee9 100644
--- a/cmd/validator.go
+++ b/cmd/validator.go
@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/0chain/gosdk/core/common"
 	"github.com/0chain/gosdk/zboxcore/sdk"
@@ -42,12 +41,12 @@ var lsValidators = &cobra.Command{
 		doJSON, _ := cmd.Flags().GetBool("json")
 		stakable, err := cmd.Flags().GetBool("stakable")
 		if err != nil {
-			log.Fatalf("error parsing stakable flag: %v", err)
+			Fatalf("error parsing stakable flag: %v", err)
 		}
 
 		list, err := sdk.GetValidators(stakable)
 		if err != nil {
-			log.Fatalf("Failed to get storage SC configurations: %v", err)
+			Fatalf("Failed to get storage SC configurations: %v", err)
 		}
 
 		if doJSON {
@@ -75,21 +74,21 @@ var validatorInfoCmd = &cobra.Command{
 
 		if flags.Changed("json") {
 			if json, err = flags.GetBool("json"); err != nil {
-				log.Fatal("invalid 'json' flag: ", err)
+				Fatal("invalid 'json' flag: ", err)
 			}
 		}
 
 		if !flags.Changed("validator_id") {
-			log.Fatal("missing required 'validator_id' flag")
+			Fatal("missing required 'validator_id' flag")
 		}
 
 		if validatorID, err = flags.GetString("validator_id"); err != nil {
-			log.Fatal("error in 'validator_id' flag: ", err)
+			Fatal("error in 'validator_id' flag: ", err)
 		}
 
 		var validator *sdk.Validator
 		if validator, err = sdk.GetValidator(validatorID); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		if json {
@@ -115,16 +114,16 @@ var validatorUpdateCmd = &cobra.Command{
 		)
 
 		if !flags.Changed("validator_id") {
-			log.Fatal("missing required 'validator_id' flag")
+			Fatal("missing required 'validator_id' flag")
 		}
 
 		if validatorID, err = flags.GetString("validator_id"); err != nil {
-			log.Fatal("error in 'validator_id' flag: ", err)
+			Fatal("error in 'validator_id' flag: ", err)
 		}
 
 		// If validator with ID does not exist, throw.
 		if _, err = sdk.GetValidator(validatorID); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		updateValidator := new(sdk.UpdateValidator)
@@ -132,11 +131,11 @@ var validatorUpdateCmd = &cobra.Command{
 		if flags.Changed("min_stake") {
 			var minStake float64
 			if minStake, err = flags.GetFloat64("min_stake"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			stake, err := common.ToBalance(minStake)
 			if err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateValidator.MinStake = &stake
 		}
@@ -144,11 +143,11 @@ var validatorUpdateCmd = &cobra.Command{
 		if flags.Changed("max_stake") {
 			var maxStake float64
 			if maxStake, err = flags.GetFloat64("max_stake"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			stake, err := common.ToBalance(maxStake)
 			if err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateValidator.MaxStake = &stake
 		}
@@ -156,7 +155,7 @@ var validatorUpdateCmd = &cobra.Command{
 		if flags.Changed("num_delegates") {
 			var nd int
 			if nd, err = flags.GetInt("num_delegates"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateValidator.NumDelegates = &nd
 		}
@@ -164,7 +163,7 @@ var validatorUpdateCmd = &cobra.Command{
 		if flags.Changed("service_charge") {
 			var sc float64
 			if sc, err = flags.GetFloat64("service_charge"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateValidator.ServiceCharge = &sc
 		}
@@ -172,13 +171,13 @@ var validatorUpdateCmd = &cobra.Command{
 		if flags.Changed("base_url") {
 			var baseURL string
 			if baseURL, err = flags.GetString("base_url"); err != nil {
-				log.Fatal(err)
+				Fatal(err)
 			}
 			updateValidator.BaseURL = &baseURL
 		}
 
 		if _, _, err = sdk.UpdateValidatorSettings(updateValidator); err != nil {
-			log.Fatal(err)
+			Fatal(err)
 		}
 
 		fmt.Println("validator settings updated successfully")
diff --git a/cmd/version.go b/cmd/version.go
index 0ebb3b8f..66f1cddf 100644
--- a/cmd/version.go
+++ b/cmd/version.go
@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"fmt"
 	"runtime/debug"
 
 	"github.com/0chain/zboxcli/util"
@@ -26,9 +25,9 @@ var versionCmd = &cobra.Command{
 			return
 		}
 
-		fmt.Println("Version info:")
-		fmt.Println("\tzbox....: ", VersionStr)
-		fmt.Println("\tgosdk...: ", getVersion("github.com/0chain/gosdk"))
+		PrintInfo("Version info:")
+		PrintInfo("\tzbox....: ", VersionStr)
+		PrintInfo("\tgosdk...: ", getVersion("github.com/0chain/gosdk"))
 	},
 }
 
@@ -36,7 +35,7 @@ func getVersion(path string) string {
 	_ = bitio.NewReader
 	bi, ok := debug.ReadBuildInfo()
 	if !ok {
-		fmt.Println("Failed to read build info")
+		PrintInfo("Failed to read build info")
 		return ""
 	}
 
diff --git a/cmd/writepool.go b/cmd/writepool.go
index 2346bcfc..691b479a 100644
--- a/cmd/writepool.go
+++ b/cmd/writepool.go
@@ -1,9 +1,6 @@
 package cmd
 
 import (
-	"fmt"
-	"log"
-
 	"github.com/0chain/gosdk/zboxcore/sdk"
 	"github.com/0chain/gosdk/zcncore"
 	"github.com/spf13/cobra"
@@ -26,36 +23,36 @@ var wpLock = &cobra.Command{
 		)
 
 		if !flags.Changed("allocation") {
-			log.Fatal("missing required 'allocation' flag")
+			Fatal("missing required 'allocation' flag")
 		}
 
 		if !flags.Changed("tokens") {
-			log.Fatal("missing required 'tokens' flag")
+			Fatal("missing required 'tokens' flag")
 		}
 
 		if allocID, err = flags.GetString("allocation"); err != nil {
-			log.Fatal("invalid 'allocation' flag: ", err)
+			Fatal("invalid 'allocation' flag: ", err)
 		}
 
 		if tokens, err = flags.GetFloat64("tokens"); err != nil {
-			log.Fatal("invalid 'tokens' flag: ", err)
+			Fatal("invalid 'tokens' flag: ", err)
 		}
 
 		if tokens < 0 {
-			log.Fatal("invalid token amount: negative")
+			Fatal("invalid token amount: negative")
 		}
 
 		if flags.Changed("fee") {
 			if fee, err = flags.GetFloat64("fee"); err != nil {
-				log.Fatal("invalid 'fee' flag: ", err)
+				Fatal("invalid 'fee' flag: ", err)
 			}
 		}
 
 		_, _, err = sdk.WritePoolLock(allocID, zcncore.ConvertToValue(tokens), zcncore.ConvertToValue(fee))
 		if err != nil {
-			log.Fatalf("Failed to lock tokens in write pool: %v", err)
+			Fatalf("Failed to lock tokens in write pool: %v", err)
 		}
-		fmt.Println("locked")
+		PrintInfo("locked")
 	},
 }
 
@@ -75,23 +72,23 @@ var wpUnlock = &cobra.Command{
 		)
 
 		if !flags.Changed("allocation") {
-			log.Fatal("missing required 'allocation' flag")
+			Fatal("missing required 'allocation' flag")
 		}
 		if allocID, err = flags.GetString("allocation"); err != nil {
-			log.Fatal("invalid 'allocation' flag: ", err)
+			Fatal("invalid 'allocation' flag: ", err)
 		}
 
 		if flags.Changed("fee") {
 			if fee, err = flags.GetFloat64("fee"); err != nil {
-				log.Fatal("invalid 'fee' flag: ", err)
+				Fatal("invalid 'fee' flag: ", err)
 			}
 		}
 
 		_, _, err = sdk.WritePoolUnlock(allocID, zcncore.ConvertToValue(fee))
 		if err != nil {
-			log.Fatalf("Failed to unlock tokens in write pool: %v", err)
+			Fatalf("Failed to unlock tokens in write pool: %v", err)
 		}
-		fmt.Println("unlocked")
+		PrintInfo("unlocked")
 	},
 }