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How does this code work? (sh.itjust.works)

submitted 2 months ago by [email protected] to c/[email protected]

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I'm studying bash, and I came across this Stackoverflow thread which contains this bit of code:

var="abcde"
echo ${var%d*}

The output is abc, but I can't figure out why. I understand that %d is used to indicate an integer number and * represents anything, but I can't figure out why those together would truncate var to only 3 characters.

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[–] [email protected] 0 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

already answered the question

Would like to add, don't do this or shoulda used Python.

Manipulating strings in bash is a mistake and creates spaghetti code. This goes for sed and awk as well.

Python equivalent

str_x = "abcde"
pos = str_x.index("d")
ret = str_x[:pos]
print(ret)

In one line, capturing the output into a bash variable

ret=$(python -c 'str_x = "abcde"; pos = str_x.index("d"); ret = str_x[:pos]; print(ret)')

[–] [email protected] 1 points 1 week ago (1 children)

Thought this was a bash community

[–] [email protected] 1 points 1 week ago

it's a bash community as long as bash is the right tool for the job. For text manipulation, not so much. In Python can also do some really stupid things. Then will get advice. They'll say, just don't do that

Which is what i'm doing here.

just don't do that