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Trimming Bash Variables – A Summary

This post should summarize the subject of stripping out bash variables, we already talked about on previous posts

Let’s say we have a bash variable (say x), which stores a string (say “ExExampleStringStr”)

Then we can do the following manipulations:

1.

This will trim out the shortest match of the pattern “Str*” from the end of the string.
Thus, y will have the value “ExExampleString”.

2.

This will trim out the longest match of the pattern “Str*” from the end of the string.
Thus, y will have the value “ExExample”.
3.

This will trim out the shortest match of the pattern “*Ex” from the beginning of the string.
Thus, y will have the value “ExampleStringStr”.
4.

This will trim out the longest match of the pattern “*Ex” from the beginning of the string.
Thus, y will have the value “ampleStringStr”. (since ExEx is the longest match of the pattern *Ex)

So remember:
# or ## = beginning
% or %% = end
## or %% = longest match
# or % = shortest match
* is a wildcard matching “any string” (including the empty string).

These tips are according to @bashcookbook‘s. I recommend following him on twitter for many useful bash tips
Have fun

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Tags: Bash