first draft

Coding-Style.md

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 ## Coding Style
+
+### This is a short brain dump which is far from being complete
+
+* Global variables 
+  * in CAPS
+  * use them only when necessary
+  * initialize them 
+  * use readonly and variable types
+  * if it's going to be a cmd line switch, there has to be also a global ENV variable which can be used without the switch (see e.g. SNEAKY or SSL_NATIVE)
+
+* local variables (all_lower_case)
+   * declare them before usage
+   * if unclear initialize them 
+
+* use "speaking variables" but don't overdo it with the length
+
+* test before PR! If it's a check you need two bad and two good examples which should work as expected (compare results e.g. with SSLlabs)
+
+* don't use backticks anymore
+
+* use double square instead of single square brackets
+
+* use [shellcheck](https://github.com/koalaman/shellcheck) if possible
+
+* especially with sed you need to be careful as GNU sed is only 80% compatible with BSD sed (`sed -i`,` \n`, `\t`, etc.). 
+
+* don't use additional binaries 
+  * if you really, really need to use an additional one make sure it's available on the system before calling it
+
+* every operation (string, etc.) which works with bash internall functions: use them whenever possible (replacing tr/sed/awk)
+
+* avoid a mix of e.g. (sed and awk) or (cut and sed) or (sed, tr and \<whatsoever\>). 
+
+* always use a return value for a function/method
+
+* use the short functions / methods
+  * count_words() / count_lines() / count_ciphers()
+  * strip_lf() / strip_spaces()
+  * toupper() 
+  * newline_to_spaces()
+  * is_number() / is_ipv4addr() / is_ipv6addr() 
+