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Full Discussion: Shell script to apply functions to multiple columns dynamically
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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LEARN ABOUT REDHAT

psc

PSC(1)							      General Commands Manual							    PSC(1)

NAME

       psc - prepare sc files

SYNOPSIS

       psc [-fLkrSPv] [-s cell] [-R n] [-C n] [-n n] [-d c]

DESCRIPTION

       Psc  is used to prepare data for input to the spreadsheet calculator sc(1).  It accepts normal ascii data on standard input.  Standard out-
       put is a sc file.  With no options, psc starts the spreadsheet in cell A0.  Strings are right justified.  All data on a line is entered	on
       the  same row; new input lines cause the output row number to increment by one.	The default delimiters are tab and space.  The column for-
       mats are set to one larger than the number of columns required to hold the largest value in the column.

OPTIONS

       -f     Omit column width calculations.  This option is for preparing data to be merged with an existing spreadsheet.  If the option is  not
	      specified, the column widths calculated for the data read by psc will override those already set in the existing spreadsheet.

       -L     Left justify strings.

       -k     Keep  all  delimiters.   This  option  causes the output cell to change on each new delimiter encountered in the input stream.   The
	      default action is to condense multiple delimiters to one, so that the cell only changes once per input data item.

       -r     Output the data by row first then column.  For input consisting of a single column, this option will result in  output  of  one  row
	      with multiple columns instead of a single column spreadsheet.

       -s cell
	      Start  the  top  left  corner  of the spreadsheet in cell.  For example, -s B33 will arrange the output data so that the spreadsheet
	      starts in column B, row 33.

       -R n   Increment by n on each new output row.

       -C n   Increment by n on each new output column.

       -n n   Output n rows before advancing to the next column.  This option is used when the input is  arranged  in  a  single  column  and  the
	      spreadsheet is to have multiple columns, each of which is to be length n.

       -d c   Use the single character c as the delimiter between input fields.

       -P     Plain numbers only.  A field is a number only when there is no imbedded [-+eE].

       -S     All numbers are strings.

       -v     Print the version of psc

SEE ALSO

       sc(1)

AUTHOR

       Robert Bond

PSC 7.16							 19 September 2002							    PSC(1)
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