diff options
Diffstat (limited to 'bash.html.markdown')
| -rw-r--r-- | bash.html.markdown | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/bash.html.markdown b/bash.html.markdown index cda877ad..8c40931e 100644 --- a/bash.html.markdown +++ b/bash.html.markdown @@ -16,6 +16,7 @@ contributors: - ["Betsy Lorton", "https://github.com/schbetsy"] - ["John Detter", "https://github.com/jdetter"] - ["Harry Mumford-Turner", "https://github.com/harrymt"] + - ["Martin Nicholson", "https://github.com/mn113"] filename: LearnBash.sh --- @@ -74,8 +75,13 @@ echo ${Variable/Some/A} # => A string # Substring from a variable Length=7 -echo ${Variable:0:$Length} # => Some st -# This will return 7 characters of the string, starting from the first char +echo ${Variable:0:Length} # => Some st +# This will return only the first 7 characters of the value +echo ${Variable: -5} # => tring +# This will return the last 5 characters (note the space before -5) + +# String length +echo ${#Variable} # => 11 # Default value for variable echo ${Foo:-"DefaultValueIfFooIsMissingOrEmpty"} @@ -174,6 +180,16 @@ then echo "This will run if $Name is Daniya OR Zach." fi +# There is also the =~ operator, which tests a string against a Regex pattern: +Email=me@example.com +if [[ "$Email" =~ [a-z]+@[a-z]{2,}\.(com|net|org) ]] +then + echo "Valid email!" +fi +# Note that =~ only works within double [[ ]] square brackets, +# which are subtly different from single [ ]. +# See http://www.gnu.org/software/bash/manual/bashref.html#Conditional-Constructs for more on this. + # Redefine command 'ping' as alias to send only 5 packets alias ping='ping -c 5' # Escape alias and use command with this name instead |