Create xargs.md

cheat-sheet/Scripting/xargs.md

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+## Usage
+
+`xargs` is about converting input lines to parameters
+
+     cat pet-names.txt | xargs          # All names in a line
+     cat pet-names.txt | xargs -2       # Only 2 names per line
+
+     find . -print0 | xargs -0          # Only safe way to iterate file paths
+
+When processing input xargs removes quotes. To prevent this use `-d$'\n'`
+
+     <some command> | xargs -d$'\n' <params>
+
+
+Use `-I` to define a replace pattern in the command specified where you can
+insert the passing value multiple times. For example construct a mv command
+that renames files:
+
+    find . -print0 | xargs -0 -I{} echo mv {} {}.old