In Bash How to remove substring matching from back of the string

Question

version=0.1.2-2-gb12431b-3.4.5

What is the best utility in bash to remove the substring starting from hyphen from back of the string(-3.4.5).

I want the new_version=0.1.2-2-gb12431b, with the substring removed. Any suggestion on what is the right way to do it.

Answer 1

Parameter Expansion (prior link is to relevant man page section):

new_version=${version%-*}

Because this is only a single %, the expression is evaluated as non-greedy, so it stops at the first dash.

Using a parameter expansion avoids any call out to external tools -- cut, awk, sed, etc -- and is thus far more efficient.

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See also:

• The Bash-Hackers Parameter Expansion Page
• BashFAQ #73 ("How can I use parameter expansion?")
• BashFAQ #100 ("How can I do string manipulations in bash?")
• The BashSheet section listing available parameter expansions