Problem
You are trying to use hex for installing dependencies but when you are behind a proxy you get the following message:
Request failed (404) ** (Mix) Package fetch failed and no cached copy available
Solution
You can use the following to set up hex (taken from the answer here:
mix hex.config http_proxy http://proxy.mycompany.com
Problem
Trying to start a new phoenix application while your node installation is old you get the following error:
Error: Brunch 2+ requires node v4.0+. Upgrade node or use older brunch for old node.js: npm i -g brunch@1 -g brunch@1
Solution
You will need to upgrade your node installation by following the steps below:
$> node -v v0.10.32 $> sudo yum install nodejs npm (if npm is not available) $> npm cache clean -f $> npm install -g n $> sudo /path/n/was/installed(ie /home/kosmas/bin/n) stable $> node -v v5.10.1
Problem
You are working on an existing rails project with many rubocop warnings and you would like to fix certain types or warnings by getting only the specified files.
Solution
So for example when you use rubocop you first get the following for all the files in the project:
rubocop 799 files inspected, 17214 offenses detected
You can get a grouping of the errors by using the following:
rubocop --format offenses 7176 Style/StringLiterals 3596 Metrics/LineLength 1031 Style/VariableName 790 Style/IndentationConsistency 548 Style/SpaceAroundOperators 423 Style/Documentation 415 Style/HashSyntax 386 Style/TrailingWhiteSpace 198 Style/SpaceAfterComma ...
If you would like to know only the files for a certain type of warning to be able to fix them you could try the following:
rubocop --only Style/TrailingWhitespace ..... list of files 799 files inspected, 386 offenses detected
Problem
You want to use some array method in a value returned, which can either be a single value or an array of values.
Solution
Rails ActiveSupport Array, provides a method called wrap, that can be used to:
Wraps its argument in an array unless it is already an array (or array-like)
Full explanation of the method here.
Thanks Miles
Problem
You would like to quickly convert a number from a different base system (i.e. binary, octal, hexadecimal), to decimal.
Solution
Use the echo $(()) shell command to convert it passing it the current base system and the number, as in $((2#101010)) or using the O for octal or 0x for hexadecimal notations.
Examples:
echo $(( 16#FF )) 255 echo $(( 0xFF )) 255 echo $(( 8#21 )) 17 echo $(( 021 )) 17
Taken from Linux Journal’s Work the Shell column (March 2016)