first draft

README.md

@@ -1 +1,116 @@
-README
+# Jan’s Shell Utilities
+
+I’m coming across having to write the same shell script bits occasionally, and I got tired of jumping backwards through my projects to find the latest version, so here is a repository.
+
+## Goals
+
+- Write once (here) and copypasta everywhere.
+- sh compatible if possible
+
+
+# Functions
+
+## `wait_for_url $url $duration $iterations`
+
+Wait for a particular URL to be available using `curl`. Wait `$duration` seconds between attempts, try `$iterations` times. Defaults to `1` seconds and `3` times.
+
+Signature:
+
+```shell
+wait_for_url url<string> [iterations<int> duration<int>]
+```
+
+Usage:
+
+```shell
+source ./wait_for_url.sh
+
+# try 3 times, 1s apart
+wait_for_url http://127.0.0.1:5984
+
+# try 5 times, 1s apart
+wait_for_url http://127.0.0.1:5984 5 3
+
+# try 5 times, 3s apart
+wait_for_url http://127.0.0.1:5984 5 3
+```
+
+## `wait_for_pid_exit $pid $duration $iterations`
+
+Wait for a particular PID to exit. Wait `$duration` seconds between attempts, try `$iterations` times. Defaults to `1` seconds and `3` times.
+
+Signature:
+
+```shell
+wait_for_pid_exit pid<int> [iterations<int> duration<int>]
+```
+
+Usage:
+
+```shell
+source ./wait_for_pid_exit.sh
+
+# try 3 times, 1s apart
+wait_for_pid_exit 3618
+
+# try 5 times, 1s apart
+wait_for_pid_exit 3618 5 3
+
+# try 5 times, 3s apart
+wait_for_pid_exit 3618 5 3
+```
+
+## `error_and_exit $message`
+
+Prints an error message and then exits with exit code `1`.
+
+Signature:
+
+```shell
+error_and_exit [message<string>]
+```
+
+Usage:
+
+```shell
+
+source ./lib
+
+# print message, then exit
+error_and_exit "this did not work"
+```
+
+TODO:
+- make exit code variable
+  - probably as `error_and_exit "msg" 17`
+
+
+## `assert_arg $arg`
+
+Assert if a particular argument has been passed to a function. Combine with `&&` and `||` for error handling and setting of defaults for optional arguments.
+
+Signature:
+
+```shell
+assert_arg arg<any>
+```
+
+Usage:
+
+```shell
+source ./lib.sh
+
+
+# fail if arg is missing
+function my_fun () {
+	assert_arg $1 && url=$1 || error_and_exit "error 'url' missing"
+	# now $url is available
+}
+
+# set arg to default value if missing
+function my_fun () {
+	assert_arg $1 && iterations=$1 || iterations=5
+	# now $iterations is available
+}
+
+```

lib.sh

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+
+function debug () {
+	if [ -n "$DEBUG" ]; then
+		echo "$1"
+	fi
+}
+
+function debug_inline () {
+	if [ -n "$DEBUG" ]; then
+		printf "$1"
+	fi
+}
+
+function error_and_exit () {
+	echo $1 || "error"
+	exit 1
+}
+
+function assert_arg () {
+	arg=$1
+
+	if [ -z "$arg" ]; then
+		return 1
+	fi
+	return 0
+}

test.sh

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+#!/bin/sh
+
+#source ./wait_for_url.sh
+# 
+# echo test1
+# (wait_for_url)
+# echo
+
+# echo test2
+# (wait_for_url http://localhost:8000 || echo "error reaching url")
+# echo "test2 done"
+# 
+# echo test3
+# (wait_for_url http://localhost:8000 4)
+# echo
+# 
+# echo test4
+# (wait_for_url http://localhost:8000 4 17)
+# echo
+
+
+source ./wait_for_pid_exit.sh
+
+echo test5
+(wait_for_pid_exit 45591 4 17)
+echo "test5 done"

wait_for_pid_exit.sh

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+
+source ./lib.sh
+
+function wait_for_pid_exit () {
+	assert_arg "$1" && pid="$1" || error_and_exit "pid not provided, exiting"
+	assert_arg "$2" && iterations="$2" || iterations=3
+	assert_arg "$3" && duration="$3" || duration=1
+
+	debug "called wait_for_url(pid=pid, duration=$duration, iterations=$iterations)"
+
+	waiting=0
+
+	debug_inline "waiting for $pid to exit "
+	until ( ! ps ax | grep $pid | grep -v grep > /dev/null); do
+		if [ $waiting -eq $iterations ]; then
+			let after=$duration*iterations
+			debug_inline "failed, $pid still running after $after seconds\n"
+			return 1
+		fi
+		debug_inline .
+		let waiting=waiting+1
+		sleep $duration
+	done
+	debug_inline " succeeded\n"
+}

wait_for_url.sh

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+
+source ./lib.sh
+
+function wait_for_url () {
+	assert_arg "$1" && url="$1" || error_and_exit "url not provided, exiting"
+	assert_arg "$2" && iterations="$2" || iterations=3
+	assert_arg "$3" && duration="$3" || duration=1
+
+	debug "called wait_for_url(url=$url, duration=$duration, iterations=$iterations)"
+
+	waiting=0
+	cmd="curl --output /dev/null --silent --insecure --head --fail --max-time 2 $url"
+
+	debug_inline "waiting for $url "
+	until ($cmd); do
+		if [ $waiting -eq $iterations ]; then
+			let after=$duration*iterations
+			debug_inline "failed, $url can not be reached after $after seconds\n"
+			return 1
+		fi
+		debug_inline .
+		let waiting=waiting+1
+		sleep $duration
+	done
+	debug_inline " succeeded\n"
+}