How can I assign the output of a function to a variable using bash

Question

I have a bash function that produces some output   function scan     echo  output      How can I assign this output to a variable   ie  VAR scan  of course this doesn t work - it makes VAR equal the string  scan

User · Accepted Answer

VAR   scan    Exactly the same way as for programs

User · Answer

I think init js should use declare instead of local   function scan3         declare -n outvar  1      -n makes it a nameref      local nl    x0a      outvar  output  nl   nl      two total  quotes preserve newlines

User · Answer

You may use bash functions in commands pipelines as you would otherwise use regular programs  The functions are also available to subshells and transitively  Command Substitution   VAR   scan    Is the straighforward way to achieve the result you want in most cases  I will outline special cases below   Preserving trailing Newlines   One of the  usually helpful  side effects of Command Substitution is that it will strip any number of trailing newlines  If one wishes to preserve trailing newlines  one can append a dummy character to output of the subshell  and subsequently strip it with parameter expansion   function scan2          local nl    x0a      that s just  n     echo  output  nl   nl     2 in the string   1 by echo      append a character to the total output    and strip it with    parameter expansion  VAR   scan2  echo  x    VAR    VAR  x    echo    VAR ---    prints  3 newlines kept    output   ---   Use an output parameter  avoiding the subshell  and preserving newlines   If what the function tries to achieve is to  return  a string into a variable   with bash v4 3 and up  one can use what s called a nameref  Namerefs allows a function to take the name of one or more variables output parameters  You can assign things to a nameref variable  and it is as if you changed the variable it  points to references    function scan3         local -n outvar  1      -n makes it a nameref      local nl    x0a      outvar  output  nl   nl      two total  quotes preserve newlines    VAR  some prior value which will get overwritten     you pass the name of the variable  VAR will be modified  scan3 VAR    newlines are also preserved  echo    VAR        prints   output        This form has a few advantages  Namely  it allows your function to modify the environment of the caller without using global variables everywhere   Note  using namerefs can improve the performance of your program greatly if your functions rely heavily on bash builtins  because it avoids the creation of a subshell that is thrown away just after  This generally makes more sense for small functions reused often  e g  functions ending in echo   returnstring   This is relevant  https   stackoverflow com a 38997681 5556676

[bash] How can I assign the output of a function to a variable using bash?

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