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Top Forums Shell Programming and Scripting Shell script to apply functions to multiple columns dynamically Post 303025730 by bakunin on Saturday 10th of November 2018 07:30:45 PM
Old 11-10-2018
Quote:
Originally Posted by mkathi
say if i want multiple columns based on the header example id,name or id,age or name,gender and hash and store the output value in a new column for each row
If you want multiple columns you need to make the variable target_id and target_idx both arrays, no?

Then there is this:
Code:
  # then, iterate over lines
  while IFS=, read -r -a line; do
    a=echo-n ${line[$target_idx]}|md5sum # if my input in target is "id"
  done
} <testfile.txt

echo$line|"$a"

You iterate over the input lines, yes, but you produce output (the echo-line) only once: after you have read all the input. This must be wrong, no? Apart from the fact that after "echo" there needs to be a space (like after any command), but i suppose that was simply a typing error.

Also this line is not correct:
Code:
a=echo-n ${line[$target_idx]}|md5sum # if my input in target is "id"

It should perhaps read:
Code:
a=$(echo -n ${line[$target_idx]}|md5sum) # if my input in target is "id"

For parametrisation via the commandline i suggest to read the man page for getopts. I have just written an example in another thread you might want to use as a starting point.

I hope this helps.

bakunin
 

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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME
atf-sh [-s shell] -- interpreter for shell-based test programs SYNOPSIS
atf-sh script DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library. atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter- preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not use any non-standard extensions. The following options are available: -s shell Specifies the shell to use instead of the value provided by ATF_SHELL. ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes. ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes. ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a specific interpreter. EXAMPLES
Scripts using atf-sh(3) should start with: #! /usr/bin/env atf-sh Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode the path to atf-sh in the script and then use the -s option afterwards as a single parameter: #! /path/to/bin/atf-sh -s/bin/bash ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts. SEE ALSO
atf-sh(3) BSD
September 27, 2014 BSD
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