Shell Programming and Scripting

Hello

i am trying to change every word that starts with "a" or "b" . if it starts with one of the letters i want to add xx rho the end of the word.

Example : boy ==> boyxx

that what i did so far

thank you

If "boy" is entered it will never equal 'a' or 'b' and so the expression will always evaluate to false.

Since you are using kshell, the right hand side of an expression in double brackets is treated as a pattern and you can code:

Code:

[[ $word == "b"* ]]

to test if the expansion of $word is a 'b' followed by zero or more characters.

The asterisk (*) must be outside of the quotes or shell will not treat it as a meta character.

If you must, or would rather, use single brackets, then you can code something like this:

Code:

[ "${word:0:1}" -eq "b" ]

Which will take the first character of the value of word and compare it to 'b.' If you try to use pattern characters inside of single brackets the shell will treat them as filename globbing characters and you'll end of with undesired results.

thank you

how can i add the "cc" to the end of the word

Ha! I missed that!

Variable expansion syntax is generally $varname, however when you need to append something to the expanded content, and adding that would form another legitimate variable name ($varnamexx for example), you need to use one of two variations to cause shell to see $varname correctly.

The preferred way putting curly braces round the variable name like either of these:

Code:

${varname}xx
${varname}"xx"

However, this will usually work too:

Code:

$varname"xx"

If what is being appended is not a legitimate variable name character (a dot forinstance) then you can code something like:

Code:

$varname.jpg

As the shell will stop parsing and recognise the end of the variable name when it encounters a non-name character.

Thank you agama very helpful

b=are
[[ $b =~ ^b ]] && echo match

Any shell:

Code:

case $word in 
  [ab]*) echo "the word is ${word}xx";;
      *) echo "the word is $word";;
esac