linux shell program summary

Posted 2020-08-09

from:Sep 23 2016

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mathematical operation:

floating number,bc calculator:

we can also use bc in shell scripts:

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if - then - else

number comparison:

              n1 -eq n2

              n1 -ge n2

              n1 -gt n2

              n1 -le n2

              n1 -lt n2

              n1 -ne n2

if - then - elif, notice that the second elif won‘t be executed, though it‘s also right.

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strings comarison:

                          str1 = str2

                          str1 != str2

                          str1 < str2

                          str1 /> str2

                          -n str1

                          -z str1

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