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

submitted 2 months ago by zarkanian@sh.itjust.works to c/bash@lemmy.ml

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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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[–] logging_strict@lemmy.ml 0 points 6 days ago* (last edited 6 days 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)')

[–] bbpngn 1 points 2 days ago (1 children)

Thought this was a bash community

[–] logging_strict@lemmy.ml 1 points 20 hours 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