Misc fixes on Python tools (#2136)

Misc fixes on Python tools
diff --git a/tools/biotop.py b/tools/biotop.py
index 2aab1fc..3fe454c 100755
--- a/tools/biotop.py
+++ b/tools/biotop.py
@@ -53,7 +53,7 @@
 diskstats = "/proc/diskstats"
 
 # signal handler
-def signal_ignore(signal, frame):
+def signal_ignore(signal_value, frame):
     print()
 
 # load BPF program
diff --git a/tools/cachetop.py b/tools/cachetop.py
index 1013675..51ddace 100755
--- a/tools/cachetop.py
+++ b/tools/cachetop.py
@@ -40,7 +40,7 @@
     "WRITE_HIT%"
 )
 DEFAULT_FIELD = "HITS"
-
+DEFAULT_SORT_FIELD = FIELDS.index(DEFAULT_FIELD)
 
 # signal handler
 def signal_ignore(signal, frame):
@@ -61,7 +61,7 @@
 
 def get_processes_stats(
         bpf,
-        sort_field=FIELDS.index(DEFAULT_FIELD),
+        sort_field=DEFAULT_SORT_FIELD,
         sort_reverse=False):
     '''
     Return a tuple containing:
@@ -223,7 +223,7 @@
             uid = int(stat[1])
             try:
                 username = pwd.getpwuid(uid)[0]
-            except KeyError as ex:
+            except KeyError:
                 # `pwd` throws a KeyError if the user cannot be found. This can
                 # happen e.g. when the process is running in a cgroup that has
                 # different users from the host.
diff --git a/tools/criticalstat.py b/tools/criticalstat.py
index 38c318d..8126b49 100755
--- a/tools/criticalstat.py
+++ b/tools/criticalstat.py
@@ -319,7 +319,7 @@
             print("NO STACK FOUND DUE TO COLLISION")
         print("===================================")
         print("")
-    except:
+    except Exception:
         sys.exit(0)
 
 b["events"].open_perf_buffer(print_event, page_cnt=256)
diff --git a/tools/fileslower.py b/tools/fileslower.py
index 0515242..219a94a 100755
--- a/tools/fileslower.py
+++ b/tools/fileslower.py
@@ -205,7 +205,7 @@
 try:
     b.attach_kprobe(event="__vfs_write", fn_name="trace_write_entry")
     b.attach_kretprobe(event="__vfs_write", fn_name="trace_write_return")
-except:
+except Exception:
     # older kernels don't have __vfs_write so try vfs_write instead
     b.attach_kprobe(event="vfs_write", fn_name="trace_write_entry")
     b.attach_kretprobe(event="vfs_write", fn_name="trace_write_return")
diff --git a/tools/filetop.py b/tools/filetop.py
index e9f67a2..91e098e 100755
--- a/tools/filetop.py
+++ b/tools/filetop.py
@@ -60,7 +60,7 @@
 loadavg = "/proc/loadavg"
 
 # signal handler
-def signal_ignore(signal, frame):
+def signal_ignore(signal_value, frame):
     print()
 
 # define BPF program
diff --git a/tools/lib/uflow_example.txt b/tools/lib/uflow_example.txt
index 5dccb8f..c7621f5 100644
--- a/tools/lib/uflow_example.txt
+++ b/tools/lib/uflow_example.txt
@@ -48,8 +48,8 @@
 3   27722  27731  3.144          <- java/lang/ThreadGroup.checkAccess
 3   27722  27731  3.144          -> java/lang/ThreadGroup.addUnstarted
 3   27722  27731  3.144          <- java/lang/ThreadGroup.addUnstarted
-3   27722  27731  3.145          -> java/lang/Thread.isDaemon     
-3   27722  27731  3.145          <- java/lang/Thread.isDaemon     
+3   27722  27731  3.145          -> java/lang/Thread.isDaemon
+3   27722  27731  3.145          <- java/lang/Thread.isDaemon
 3   27722  27731  3.145          -> java/lang/Thread.getPriority   
 3   27722  27731  3.145          <- java/lang/Thread.getPriority   
 3   27722  27731  3.145          -> java/lang/Thread.getContextClassLoader
diff --git a/tools/llcstat.py b/tools/llcstat.py
index b491543..01a63fd 100755
--- a/tools/llcstat.py
+++ b/tools/llcstat.py
@@ -85,7 +85,7 @@
     b.attach_perf_event(
         ev_type=PerfType.HARDWARE, ev_config=PerfHWConfig.CACHE_REFERENCES,
         fn_name="on_cache_ref", sample_period=args.sample_period)
-except:
+except Exception:
     print("Failed to attach to a hardware event. Is this a virtual machine?")
     exit()
 
diff --git a/tools/runqslower.py b/tools/runqslower.py
index da8d486..0b3e1c1 100755
--- a/tools/runqslower.py
+++ b/tools/runqslower.py
@@ -218,7 +218,7 @@
 else:
     bpf_text = bpf_text.replace('FILTER_US', 'delta_us <= %s' % str(min_us))
 if args.pid:
-    bpf_text = bpf_text.replace('FILTER_PID', 'pid != %s' % pid)
+    bpf_text = bpf_text.replace('FILTER_PID', 'pid != %s' % args.pid)
 else:
     bpf_text = bpf_text.replace('FILTER_PID', '0')
 if debug or args.ebpf: