HPR3625: Shell Tips and Snippets - Collaborative Effort

Hacker Public Radio

Carl talks about a method to move function definitions to the bottom of a script using sed:

#!/bin/sh source <(sed '1,/^exit/ d' $0) __say "hello" exit __say() { echo $1 } 

Guest Host #1 (scroll to the bottom to ruin the surprise) talks about the shift command using this example:

startdate="$1" # Pick up date shift days=0 # Loop through args and create events while [ $1 ] ; do # as many times as you add a timestamp [ $1 != "off" ] && khal new $(date -j -v+"$days"d -f %Y-%m-%d +%Y-%m-%d $startdate) $1 8H Work let days++ shift done 

Guest Host #2 provides tips and examples on how to use variables safely and politely provide default values. One example of assigning a default value is:

foo=${foo:-"blah"} 

Carl then closes out with the : (colon) shell builtin and provides a variation on the above default value:

: ${foo:="blah"}