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--- linux:nice-to-know [2019/05/06 16:50] – michael
+++ linux:nice-to-know [2019/05/06 17:33] (current) – michael
@@ Line 117: / Line 117: @@
 </WRAP>
+----
+<WRAP center round box 100%>
+''<wrap hi>**curl only write to file if successful status 200**</wrap>''
+Make curl get the contents of a URL and write to file, but only write to file if the response is successful:
+<code># curl -s -S -f -o blackgate-feed.json "$blackgate_rz"</code>
+  * -s keeps curl quiet by hiding progress meter and error messages
+  * -S shows an error message if it fails (stderr)
+  * -f Fail silently (no output at all) on server errors, keeping stdout clean
+  * -o specifies an output file
+</WRAP>
+----
+<WRAP center round box 100%>
+''<wrap hi>**Pipe video stream from raspberry pi to local computer with ffplay**</wrap>''
+I use this to get a live video stream from my Raspberry Pi with Camera attached
+Execute this on the Pi, where TARGET_IP is my local computer where I will watch the stream, and PORT is an arbitrary port number.
+<code># raspivid -t 999999 -o - | nc -u $TARGET_IP $PORT</code>
+Execute this on the local computer where you will watch the video stream
+<code># nc -ul $PORT | ffplay -</code>
+----
+  * https://www.raspberrypi.org/blog/camera-board-available-for-sale/
+  * https://blog.philippklaus.de/2013/06/using-the-raspberry-pi-camera-board-on-arch-linux-arm/
+</WRAP>
+----
+<WRAP center round box 100%>
+''<wrap hi>**Generating a pseudorandom password or string in Linux bash**</wrap>''
+''Define a function in e.g. **~/.bashrc**''
+<sxh plain; gutter: false;>
+genpasswd() {
+  tr -dc A-Za-z0-9 < /dev/urandom | head -c ${1:-36} | xargs
+}
+</sxh>
+Where 36 is default length if no parameter is given
+----
+**Usage**:
+<code># genpasswd
+GVQ3ZHqrBRDzB1QwASA9uk6YsZPto2GWeRWR
+# genpasswd 7
+qvPWx7N</code>
+</WRAP>