diff --git a/contrib/pyzfs/libzfs_core/test/test_libzfs_core.py b/contrib/pyzfs/libzfs_core/test/test_libzfs_core.py
index a841f96af3..08b58b5d1e 100644
--- a/contrib/pyzfs/libzfs_core/test/test_libzfs_core.py
+++ b/contrib/pyzfs/libzfs_core/test/test_libzfs_core.py
@@ -154,8 +154,8 @@ def os_open(name, mode):
 
 @contextlib.contextmanager
 def dev_null():
-    with os_open('/dev/null', os.O_WRONLY) as fd:
-        yield fd
+    with tempfile.TemporaryFile(suffix='.zstream') as fd:
+        yield fd.fileno()
 
 
 @contextlib.contextmanager
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_receive/zfs_receive_005_neg.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_receive/zfs_receive_005_neg.ksh
index 4cbc7e3390..ce89c68357 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_receive/zfs_receive_005_neg.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_receive/zfs_receive_005_neg.ksh
@@ -82,8 +82,8 @@ log_must zfs snapshot $init_snap
 log_must eval "zfs send $init_snap > $full_bkup"
 
 log_note "'zfs receive' fails with invalid send streams."
-log_mustnot eval "zfs receive $rst_init_snap < /dev/zero"
-log_mustnot eval "zfs receive -d $rst_root </dev/zero"
+log_mustnot eval "cat </dev/zero | zfs receive $rst_init_snap"
+log_mustnot eval "cat </dev/zero | zfs receive -d $rst_root"
 
 log_must eval "zfs receive $rst_init_snap < $full_bkup"
 
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send-b.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send-b.ksh
index 87997e76c2..2105bc4d23 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send-b.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send-b.ksh
@@ -58,13 +58,13 @@ log_must zfs set "org.openzfs:snapprop=val" "$SENDFS@s1"
 # 2. Verify command line options interact with '-b' correctly
 typeset opts=("" "p" "Rp" "cew" "nv" "D" "DLPRcenpvw")
 for opt in ${opts[@]}; do
-	log_must eval "zfs send -b$opt $SENDFS@s1 > /dev/null"
-	log_must eval "zfs send -b$opt -i $SENDFS@s1 $SENDFS@s2 > /dev/null"
-	log_must eval "zfs send -b$opt -I $SENDFS@s1 $SENDFS@s2 > /dev/null"
+	log_must eval "zfs send -b$opt $SENDFS@s1 >$TEST_BASE_DIR/devnull"
+	log_must eval "zfs send -b$opt -i $SENDFS@s1 $SENDFS@s2 >$TEST_BASE_DIR/devnull"
+	log_must eval "zfs send -b$opt -I $SENDFS@s1 $SENDFS@s2 >$TEST_BASE_DIR/devnull"
 done
 for opt in ${opts[@]}; do
-	log_mustnot eval "zfs send -b$opt $SENDFS > /dev/null"
-	log_mustnot eval "zfs send -b$opt $SENDFS#bm > /dev/null"
+	log_mustnot eval "zfs send -b$opt $SENDFS >$TEST_BASE_DIR/devnull"
+	log_mustnot eval "zfs send -b$opt $SENDFS#bm >$TEST_BASE_DIR/devnull"
 done
 
 # Do 3..6 in a loop to verify various combination of "zfs send" options
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_003_pos.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_003_pos.ksh
index 825a10d0f8..0b55254f75 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_003_pos.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_003_pos.ksh
@@ -61,7 +61,7 @@ log_must zfs snapshot $snap2
 
 typeset -i i=0
 while (( i < ${#args[*]} )); do
-	log_must eval "zfs send -i ${args[i]} > /dev/null"
+	log_must eval "zfs send -i ${args[i]} >$TEST_BASE_DIR/devnull"
 
 	(( i += 1 ))
 done
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_004_neg.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_004_neg.ksh
index 4a9d29fce1..dfa9fc251d 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_004_neg.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_004_neg.ksh
@@ -96,7 +96,7 @@ log_must zfs snapshot $snap3
 typeset -i i=0
 while (( i < ${#badargs[*]} ))
 do
-	log_mustnot eval "zfs send ${badargs[i]} >/dev/null"
+	log_mustnot eval "zfs send ${badargs[i]} >$TEST_BASE_DIR/devnull"
 
 	(( i = i + 1 ))
 done
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_005_pos.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_005_pos.ksh
index 9f369e372d..c9e37cbbad 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_005_pos.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_005_pos.ksh
@@ -61,6 +61,6 @@ log_must zfs snapshot -r $TESTPOOL@snap
 log_must zpool export $TESTPOOL
 log_must zpool import -o readonly=on $TESTPOOL
 
-log_must eval "zfs send -R $TESTPOOL@snap >/dev/null"
+log_must eval "zfs send -R $TESTPOOL@snap >$TEST_BASE_DIR/devnull"
 
 log_pass "'zfs send -R' can send from read-only pools"
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted.ksh
index 490e146ba6..1e63b29ade 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted.ksh
@@ -62,15 +62,15 @@ log_must eval "echo $passphrase1 | zfs create -o encryption=on" \
 
 log_must zfs snapshot -r $snap
 
-log_must eval "zfs send $snap > /dev/null"
-log_mustnot eval "zfs send -p $snap > /dev/null"
-log_mustnot eval "zfs send -R $snap > /dev/null"
+log_must eval "zfs send $snap >$TEST_BASE_DIR/devnull"
+log_mustnot eval "zfs send -p $snap >$TEST_BASE_DIR/devnull"
+log_mustnot eval "zfs send -R $snap >$TEST_BASE_DIR/devnull"
 
 log_must zfs unmount $TESTPOOL/$TESTFS1
 log_must zfs unload-key $TESTPOOL/$TESTFS1
 
-log_mustnot eval "zfs send $snap > /dev/null"
-log_must eval "zfs send $TESTPOOL/$TESTFS1/child@snap > /dev/null"
+log_mustnot eval "zfs send $snap >$TEST_BASE_DIR/devnull"
+log_must eval "zfs send $TESTPOOL/$TESTFS1/child@snap >$TEST_BASE_DIR/devnull"
 
 log_pass "ZFS performs unencrypted sends of encrypted datasets, unless the" \
 	"'-p' or '-R' options are specified"
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted_unloaded.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted_unloaded.ksh
index 112ee1143d..9d59494fc6 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted_unloaded.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted_unloaded.ksh
@@ -53,7 +53,7 @@ log_must eval "echo $passphrase | zfs create -o encryption=on" \
 log_must zfs snapshot $snap
 log_must zfs unmount $TESTPOOL/$TESTFS1
 log_must zfs unload-key $TESTPOOL/$TESTFS1
-log_mustnot eval "zfs send $snap > /dev/null"
+log_mustnot eval "zfs send $snap >$TEST_BASE_DIR/devnull"
 
 log_pass "ZFS does not perform unencrypted sends from encrypted datasets" \
 	"with unloaded keys."
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_raw.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_raw.ksh
index 85cc7407e1..065eea3ebd 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_raw.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_raw.ksh
@@ -59,21 +59,21 @@ log_must eval "echo $passphrase | zfs create -o encryption=on" \
 log_must zfs snapshot $snap
 log_must zfs snapshot $snap1
 
-log_must eval "zfs send -w $snap > /dev/null"
-log_must eval "zfs send -w $snap1 > /dev/null"
+log_must eval "zfs send -w $snap >$TEST_BASE_DIR/devnull"
+log_must eval "zfs send -w $snap1 >$TEST_BASE_DIR/devnull"
 
 log_note "Verify ZFS can perform raw sends with properties"
-log_must eval "zfs send -wp $snap > /dev/null"
-log_must eval "zfs send -wp $snap1 > /dev/null"
+log_must eval "zfs send -wp $snap >$TEST_BASE_DIR/devnull"
+log_must eval "zfs send -wp $snap1 >$TEST_BASE_DIR/devnull"
 
 log_note "Verify ZFS can perform raw replication sends"
-log_must eval "zfs send -wR $snap > /dev/null"
-log_must eval "zfs send -wR $snap1 > /dev/null"
+log_must eval "zfs send -wR $snap >$TEST_BASE_DIR/devnull"
+log_must eval "zfs send -wR $snap1 >$TEST_BASE_DIR/devnull"
 
 log_note "Verify ZFS can perform a raw send of an encrypted datasets with" \
 	"its key unloaded"
 log_must zfs unmount $TESTPOOL/$TESTFS1
 log_must zfs unload-key $TESTPOOL/$TESTFS1
-log_must eval "zfs send -w $snap1 > /dev/null"
+log_must eval "zfs send -w $snap1 >$TEST_BASE_DIR/devnull"
 
 log_pass "ZFS performs raw sends of datasets"
diff --git a/tests/zfs-tests/tests/functional/redacted_send/redacted_negative.ksh b/tests/zfs-tests/tests/functional/redacted_send/redacted_negative.ksh
index 432460fa2f..e591cca0bb 100755
--- a/tests/zfs-tests/tests/functional/redacted_send/redacted_negative.ksh
+++ b/tests/zfs-tests/tests/functional/redacted_send/redacted_negative.ksh
@@ -45,11 +45,11 @@ log_must zfs snapshot $clone2@snap
 
 # Incompatible flags
 log_must zfs redact $sendfs@snap2 book $clone1@snap
-log_mustnot eval "zfs send -R --redact book $sendfs@snap2 >/dev/null"
+log_mustnot eval "zfs send -R --redact book $sendfs@snap2 >$TEST_BASE_DIR/devnull"
 
 typeset arg
 for arg in "$sendfs" "$clone1#book"; do
-	log_mustnot eval "zfs send --redact book $arg >/dev/null"
+	log_mustnot eval "zfs send --redact book $arg >$TEST_BASE_DIR/devnull"
 done
 
 # Bad redaction list arguments
@@ -58,7 +58,7 @@ log_mustnot zfs redact $sendfs@snap1 book
 log_mustnot zfs redact $sendfs#book1 book4 $clone1
 log_mustnot zfs redact $sendfs@snap1 book snap2 snap3
 log_mustnot zfs redact $sendfs@snap1 book @snap2 @snap3
-log_mustnot eval "zfs send --redact $sendfs#book $sendfs@snap >/dev/null"
+log_mustnot eval "zfs send --redact $sendfs#book $sendfs@snap >$TEST_BASE_DIR/devnull"
 
 # Redaction snapshots not a descendant of tosnap
 log_mustnot zfs redact $sendfs@snap2 book $sendfs@snap2
@@ -66,7 +66,7 @@ log_must zfs redact $sendfs@snap2 book2 $clone1@snap $clone2@snap
 log_must eval "zfs send --redact book2 $sendfs@snap2 >$stream"
 log_must zfs redact $sendfs@snap2 book3 $clone1@snap $clone2@snap
 log_must eval "zfs send -i $sendfs@snap1 --redact book3 $sendfs@snap2 \
-    >/dev/null"
+    >$TEST_BASE_DIR/devnull"
 log_mustnot zfs redact $sendfs@snap3 $sendfs@snap3 $clone1@snap
 
 # Full redacted sends of redacted datasets are not allowed.
diff --git a/tests/zfs-tests/tests/functional/redacted_send/redacted_resume.ksh b/tests/zfs-tests/tests/functional/redacted_send/redacted_resume.ksh
index 8118ea59ec..4ab04a0e57 100755
--- a/tests/zfs-tests/tests/functional/redacted_send/redacted_resume.ksh
+++ b/tests/zfs-tests/tests/functional/redacted_send/redacted_resume.ksh
@@ -81,7 +81,7 @@ log_must eval "zfs send --redact book1 $sendfs@snap >$stream"
 dd if=$stream bs=64k count=1 | log_mustnot zfs receive -s $recvfs
 [[ "-" = $(get_prop receive_resume_token $recvfs) ]] && \
     log_fail "Receive token not found."
-log_mustnot eval "zfs send --saved --redact book1 $recvfs > /dev/null"
+log_mustnot eval "zfs send --saved --redact book1 $recvfs >$TEST_BASE_DIR/devnull"
 log_must zfs recv -A $recvfs
 log_must datasetnonexists $recvfs
 
diff --git a/tests/zfs-tests/tests/functional/removal/removal_with_send.ksh b/tests/zfs-tests/tests/functional/removal/removal_with_send.ksh
index 59e66aca52..a082478381 100755
--- a/tests/zfs-tests/tests/functional/removal/removal_with_send.ksh
+++ b/tests/zfs-tests/tests/functional/removal/removal_with_send.ksh
@@ -28,7 +28,7 @@ function callback
 {
 	create_snapshot $TESTPOOL/$TESTFS $TESTSNAP
 	log_must ksh -c \
-	    "zfs send $TESTPOOL/$TESTFS@$TESTSNAP >/dev/null"
+	    "zfs send $TESTPOOL/$TESTFS@$TESTSNAP >$TEST_BASE_DIR/devnull"
 	return 0
 }
 
diff --git a/tests/zfs-tests/tests/functional/rsend/send_invalid.ksh b/tests/zfs-tests/tests/functional/rsend/send_invalid.ksh
index a0abe64b4c..2ce7ee4a08 100755
--- a/tests/zfs-tests/tests/functional/rsend/send_invalid.ksh
+++ b/tests/zfs-tests/tests/functional/rsend/send_invalid.ksh
@@ -44,7 +44,7 @@ log_must zfs snap $testfs@snap0
 log_must zfs snap $testfs@snap1
 
 # Test bad send with the CLI
-log_mustnot eval "zfs send -i $testfs@snap1 $testfs@snap0 >/dev/null"
+log_mustnot eval "zfs send -i $testfs@snap1 $testfs@snap0 >$TEST_BASE_DIR/devnull"
 
 # Test bad send with libzfs/libzfs_core
 log_must badsend $testfs@snap0 $testfs@snap1
diff --git a/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh b/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh
index d5eb9a0edc..c390327a5b 100755
--- a/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh
+++ b/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh
@@ -103,7 +103,7 @@ set -A badargs \
 
 while (( i < ${#badargs[*]} ))
 do
-	log_mustnot eval "zfs send --saved ${badargs[i]} >/dev/null"
+	log_mustnot eval "zfs send --saved ${badargs[i]} >$TEST_BASE_DIR/devnull"
 	(( i = i + 1 ))
 done