From 3787db0fe3dcc8962eceeb3556e9b91825d9f067 Mon Sep 17 00:00:00 2001
From: perro <hi@perrotuerto.blog>
Date: Wed, 15 Mar 2023 09:53:55 -0700
Subject: [PATCH] Ejercicios 12f-h

---
 exercises/ex12/false |  7 +++++++
 exercises/ex12/tail  | 45 ++++++++++++++++++++++++++++++++++++++++++++
 exercises/ex12/yes   | 12 ++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100755 exercises/ex12/false
 create mode 100755 exercises/ex12/tail
 create mode 100755 exercises/ex12/yes

diff --git a/exercises/ex12/false b/exercises/ex12/false
new file mode 100755
index 0000000..7cd6371
--- /dev/null
+++ b/exercises/ex12/false
@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+# Exercise 12h
+# false command
+
+import sys
+
+sys.exit(1)
diff --git a/exercises/ex12/tail b/exercises/ex12/tail
new file mode 100755
index 0000000..bb5f899
--- /dev/null
+++ b/exercises/ex12/tail
@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+# Exercise 12f
+# tail command
+
+import sys
+import argparse
+from pathlib import Path
+
+parser = argparse.ArgumentParser()
+parser.add_argument("stream", default=sys.stdin, nargs="*")
+parser.add_argument("-v", "--verbose", action="store_true")
+parser.add_argument("-n", "--lines", default="10", type=str)
+args = parser.parse_args()
+res = []
+
+
+def intonum(n):
+    try:
+        return abs(int(n))
+    except ValueError:
+        print(f"tail: el número de líneas no es válido: «{n}»")
+        sys.exit(1)
+
+
+def getlines(lines, n):
+    lines = list(map(lambda l: l.rstrip(), lines))
+    num = intonum(n)
+    if n[0] == "+":
+        return lines[num-1:]
+    return lines[-num:]
+
+
+if isinstance(args.stream, list):
+    for path in args.stream:
+        lines = Path(path).open().readlines()
+        header = [""] if len(res) != 0 else []
+        if args.verbose:
+            header += [f"==> {path} <=="]
+        res += header + getlines(lines, args.lines)
+else:
+    lines = args.stream.readlines()
+    header = ["==> entrada estándar <=="] if args.verbose else []
+    res += header + getlines(lines, args.lines)
+
+print("\n".join(res))
diff --git a/exercises/ex12/yes b/exercises/ex12/yes
new file mode 100755
index 0000000..bba45e5
--- /dev/null
+++ b/exercises/ex12/yes
@@ -0,0 +1,12 @@
+#!/usr/bin/env python
+# Exercise 12g
+# yes command
+
+import argparse
+
+parser = argparse.ArgumentParser()
+parser.add_argument("words", nargs="*", type=str, default=["y"])
+args = parser.parse_args()
+
+while True:
+    print(" ".join(args.words))