From c0a7566a2025479e906a539d2c1bca9022efc2c8 Mon Sep 17 00:00:00 2001
From: Jakob Kaivo <jkk@ung.org>
Date: Tue, 18 Feb 2020 16:13:41 -0500
Subject: initial version

---
 README.md   | 26 ++++++++++++++++++++++++++
 dirstack.sh | 20 ++++++++++++++++++++
 history.sh  |  3 +++
 shell.sh    | 20 ++++++++++++++++++++
 4 files changed, 69 insertions(+)
 create mode 100644 README.md
 create mode 100644 dirstack.sh
 create mode 100644 history.sh
 create mode 100644 shell.sh

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..55dc9e3
--- /dev/null
+++ b/README.md
@@ -0,0 +1,26 @@
+This is a collection of shell functions that can give any POSIX shell some
+of Bash's extra functionality. The functions are split into groups of related
+functionality. To install them into your shell, use the `.` command to read
+the appropriate script (e.g. to load `shell.sh`, run `. ./shell.sh`).
+
+`shell.sh`
+----------
+Functionality related to the operation of the shell itself.
+
+- `suspend` - Suspends a non-login shell.
+- `logout` - Exits a login shell.
+- `source` - Alternative spelling of `.`.
+
+`dirstack.sh`
+-------------
+Functionality for maintaining a stack of working directories.
+
+- `pushd` - Enter a new directory and add the previous to the stack.
+- `popd` - Pop the top directory from the stack and change to it.
+- `dirs` - Print out the current directory stack.
+
+`history.sh`
+------------
+Funcionality related to command line history.
+
+- `history` - Lists the current command history.
diff --git a/dirstack.sh b/dirstack.sh
new file mode 100644
index 0000000..37c3bf3
--- /dev/null
+++ b/dirstack.sh
@@ -0,0 +1,20 @@
+pushd() {
+	_topush=$(pwd)
+	cd "${1+"$@"}" && _DIRSTACK="$(printf '%s\n' ${_topush} ${_DIRSTACK})"
+	unset _topush
+}
+
+popd() {
+	if [ -z "${_DIRSTACK}" ]; then
+		printf 'popd: directory stack is empty\n'
+		return 1
+	fi
+
+	cd $(dirs | head -n1)
+	pwd
+	_DIRSTACK="$(dirs | tail +2)"
+}
+
+dirs() {
+	printf '%s\n' ${_DIRSTACK}
+}
diff --git a/history.sh b/history.sh
new file mode 100644
index 0000000..ce2d87f
--- /dev/null
+++ b/history.sh
@@ -0,0 +1,3 @@
+history() {
+	fc -l
+}
diff --git a/shell.sh b/shell.sh
new file mode 100644
index 0000000..45cf5cf
--- /dev/null
+++ b/shell.sh
@@ -0,0 +1,20 @@
+suspend() {
+	if [ x"$0" -ne x"${0#-}" ]; then
+		#TODO: handle -f
+		printf 'suspend: not suspending login shell\n' >&2
+	else
+		kill -STOP $$
+	fi
+}
+
+logout() {
+	if [ x"$0" -ne x"${0#-}" ]; then
+	 	printf 'logout: use exit to leave non-login shell\n' >&2
+	else
+		exit "$@"
+	fi
+}
+
+source() {
+	. "$@"
+}
-- 
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