All posts for the month March, 2022

shell glob


glob is not, and much more limited than, RegEx
Assuming a1.txt and a2.txt exists in current folder.
In addition to * and ?: 

square bracket for range: [] range of characters
    ls a[1-3].txt  # output a1.txt  a2.txt
	also [[:lower:]]  upper alnum alpha blank digit punct space xdigit

exclamation mark for Complementation !: for single char, not 1 and not 2
	ls a[!12].txt  # output cannot access 'a[!12].txt' 
    
curly braces: no space allowed in {}
    ls -l a{1,2,3}.txt  # same as ls -l a1.txt a2.txt a3.txt
    I feel this is brace expansion, instead of globbing since nothing to do with file existence
by Rio Wing on March 27, 2022  •  Permalink
Posted in linux

Posted by Rio Wing on March 27, 2022

https://riowingwp.wordpress.com/2022/03/27/shell-glob/

SDI


Serial digital interface uses BNC connector with coaxial cable.

For professionals
HDSDI can do 1.5 Gbit/second, 100 meters, for broadcast, up to 1080p
also 12G-SDI

Comparing to HDMI:
longer distance. HDMI about 10m
connector strong and secure: HDMI cannot lock.
No HDCP

There are Converters between the two

by Rio Wing on March 20, 2022  •  Permalink
Posted in video
Tagged ,

Posted by Rio Wing on March 20, 2022

https://riowingwp.wordpress.com/2022/03/20/sdi/

compiledb


A minimum compile_commands.json
The project: proj\Console\bryan cross compiled on WSL1 to generate executable for arm/linux
To Install:
$ pip install compiledb #no sudo needed
To generate this .json file:
$ compiledb make -f makebryan
makebryan is the makefile similar to the one posted on 220227
To use this .json for vsCode intellisense:
add file name to \bryan\make.vscode\c_cpp_properties.json around here:
json.configurations[].compileCommands being compile_commands.json

The file structure: array with each element being a compiling unit. compile_commands.json:

[
 {
  "directory": "/mnt/s/rio/proj/Console/bryan/make", 
  "arguments": [
   "/mnt/s/Rio/arm-mySample-linux-gnueabi/gcc-8/20190523/bin/arm-linux-g++", 
   "-g", 
   "-c", 
   "bryan.cpp", 
   "-o", 
   "../tmp/bryan.o", 
   "-I../incl"
  ], 
  "file": "bryan.cpp"
 }, 
 {
  "directory": "/mnt/s/rio/proj/Console/bryan/make", 
  "arguments": [
   "/mnt/s/Rio/arm-mySample-linux-gnueabi/gcc-8/20190523/bin/arm-linux-g++", 
   "-g", 
   "-c", 
   "bryan2.cpp", 
   "-o", 
   "../tmp/bryan2.o"
  ], 
  "file": "bryan2.cpp"
 }
]
by Rio Wing on March 13, 2022  •  Permalink
Posted in intermediate

Posted by Rio Wing on March 13, 2022

https://riowingwp.wordpress.com/2022/03/13/compiledb/

getopts


Parsing bash script parameters, as below:
Expected pameters: -a -b must have parameter like aV bV, -c has no parameter, -d is invalid as not lised in getopts’s first argument string
Code: opt.sh

TestGetOpts() 
{
    while getopts ":a:b:c" opt; do  #":a:"
        case $opt in
            a)
                echo "-$opt received with value $OPTARG" >&2
                ;;
            b)
                echo "-$opt received with value $OPTARG" >&2
                ;;
            \?)
                echo "Invalid option: -$OPTARG" >&2
                ;;
            :)
                echo "Option -$OPTARG requires an argument." >&2
                ;;
        esac
        echo -e "done opt=$opt  OPTARG=$OPTARG \n"
    done
}
TestGetOpts  $@

Command line:

$ ./opt.sh  -a aV -c -d -b

Output:

-a received with value aV  # all good as expected
done opt=a  OPTARG=aV

done opt=c  OPTARG=	# all good as expected as c doesn't expect parameter

Invalid option: -d	# d not valid as it's not in ":a:b:c"
done opt=?  OPTARG=d

Option -b requires an argument.	# some value has to follow -b as indicated by "b:"
done opt=:  OPTARG=b

by Rio Wing on March 6, 2022  •  Permalink
Posted in linux
Tagged ,

Posted by Rio Wing on March 6, 2022

https://riowingwp.wordpress.com/2022/03/06/getopts/