issues with bash commands as variables (monero.town)

submitted 10 months ago* (last edited 10 months ago) by shortwavesurfer@monero.town to c/programming@beehaw.org

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Any ideas? I am attempting to write a script that uses sed.

If done this way it fails

rmdec="sed 's/..................$//'"
i1xmr=$(echo "$i1p/$apiresponse*1000" |bc -l |$rmdec)

But if i do it this way it works

i1xmr=$(echo "$i1p/$apiresponse*1000" |bc -l | sed 's/..................$//')

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[-] bizdelnick@lemmy.ml 3 points 10 months ago* (last edited 9 months ago)

Your mistake is that after variable substitution bash does not handle quoted strings, i.e. it does not remove single quotes from sed command line. If you really need this to happen, you have to use eval:

i1xmr=$(echo "$i1p/$apiresponse*1000" | bc -l | eval $rmdec)

However using functions is a better solution in general. But in this particular case, I guess, you only need to change the bc's scale instead of using sed:

i1xmr=$(echo "scale=17; $i1p/$apiresponse*1000" | bc -l)

For better readability you may use heredoc instead of echo:

i1xmr=$( bc -l &lt;&lt; EOF
scale=17
$i1p/$apiresponse*1000
EOF
)

[-] shortwavesurfer@monero.town 1 points 10 months ago

Oh dear Lord, and see, this is why I do not code for a living. What I ended up doing is using a function like this

rmdec() { sed 's/..................$//'; }
i1xmr=$(echo "$i1p/$apiresponse*1000" |bc -l |rmdec)

this post was submitted on 24 Oct 2023

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