Index: utils/lit/tests/Inputs/shtest-format/external_shell/fail.txt
===================================================================
--- utils/lit/tests/Inputs/shtest-format/external_shell/fail.txt
+++ utils/lit/tests/Inputs/shtest-format/external_shell/fail.txt
@@ -2,4 +2,4 @@
 #
 # RUN: echo "line 1: failed test output on stdout"
 # RUN: echo "line 2: failed test output on stdout"
-# RUN: cat "does-not-exist"
+# RUN: tail "does-not-exist"
Index: utils/lit/tests/shtest-format.py
===================================================================
--- utils/lit/tests/shtest-format.py
+++ utils/lit/tests/shtest-format.py
@@ -16,7 +16,7 @@
 # CHECK-NEXT: line 2: failed test output on stdout
 # CHECK: Command Output (stderr):
 # CHECK-NEXT: --
-# CHECK-NEXT: cat: does-not-exist: No such file or directory
+# CHECK-NEXT: tail: cannot open 'does-not-exist' for reading: No such file or directory
 # CHECK: --
 
 # CHECK: FAIL: shtest-format :: external_shell/fail_with_bad_encoding.txt