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coproc:tldr:d3ee2
coproc: Create and use a coprocess running `bc`.
$ coproc BC { bc --mathlib; }; echo "1/3" >&"${BC[1]}"; read output <&"${BC[0]}"; echo "$output"
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This command sets up a coprocess, which is a form of process substitution in the shell. A coprocess allows you to communicate with a command as if it were a file.
Here is a breakdown of the command:
-
coproc BC { bc --mathlib; }
:coproc
is the keyword used to establish a coprocess.BC
is the name of the coprocess, which is used as an array variable to refer to the input/output file descriptors of the coprocess.{ bc --mathlib; }
is the command that the coprocess runs. In this case, it launches thebc
command with the--mathlib
option, which loads the math library for advanced mathematical calculations.
-
echo "1/3" >&"${BC[1]}"
:echo "1/3"
outputs the string "1/3".>&"${BC[1]}"
redirects the output of theecho
command to the coprocess's input file descriptor.${BC[1]}
is the second element (index 1) of theBC
coprocess array, which refers to the output file descriptor of the coprocess.
-
read output <&"${BC[0]}"
:read output
reads input from the coprocess's output file descriptor and stores it in the variableoutput
.<&"${BC[0]}"
redirects the coprocess's output file descriptor to the input of theread
command.${BC[0]}
is the first element (index 0) of theBC
coprocess array, which refers to the input file descriptor of the coprocess.
-
echo "$output"
:echo "$output"
outputs the value stored in theoutput
variable, which is the result of the previous calculation performed by the coprocess.
To summarize, the command establishes a coprocess running the bc
command with the math library enabled. It then sends the string "1/3" to the coprocess for calculation, reads the output from the coprocess, and finally, prints the result. In this case, the result should be "0.33333333333333333333" (the decimal representation of 1/3 according to bc
's math library).
This explanation was created by an AI. In most cases those are correct. But please always be careful and
never run a command you are not sure if it is safe.