bash: functions containing part of AWK code

Question

within of my bash code I have a part of an sed + AWK code, which do interatively some operation on input file and add the results to another txt file (the both filles had been created by the same bash script, and can be stored as different variables).

#sed removing some lines in input fille "${file}".xvg, defined in the begining of bash script
sed -i '' -e '/^[#@]/d' "${file}".xvg
# AWK measure XMAX and YMAX in the input file
# adding these outputs as two lines in another batch.bfile, which is going to be used for something
awk '
  NR==1{
    max1=$1
    max2=$2
  }
  $1>max1{max1=$1}
  $2>max2{max2=$2}
  END{printf "WORLD XMAX %s\nWORLD YMAX %s\n",max1+0.5,max2+0.5'} "${file}".xvg >> "${tmp}"/batch.bfile

is it possible to combine the both (sed +awk ) actions into some function (defined in the beggining of my bash script) and then use it as one line command within the script (in more sophisticated cas it will be applied on many filles within FOR loop)?

Here is example of my version:

#!/bin/bash


#folder with batch file
home=$PWD
tmp="${home}"/tmp


## define some functions for file processing
bar_xvg_proc () {
##AWK procession of XVG file: only for bar plot;
sed -i '' -e '/^[#@]/d' ${file}
# check XMAX and YMAX for each XVG
awk '
  NR==1{
    max1=$1
    max2=$2
  }
  $1>max1{max1=$1}
  $2>max2{max2=$2}
  END{printf "WORLD XMAX %s\nWORLD YMAX %s\n",max1+0.5,max2+0.5'} ${file} >> "${tmp}"/grace2.bfile

}
###

bar_xvg_proc "${home}"/test.xvg

and here is an error from sed

sed: -i may not be used with stdin

BUT if I define my test.xvg as a new variable $file="${home}"/test.xvg before calling my function in the script - it works well. How I could use this function directly with input file (w/o the specific variable assigned to the file )?

Here is my xvg file:

# Created by:
#                     :-) GROMACS - gmx cluster, 2019.3 (-:
# 
# Executable:   /usr/local/bin/../Cellar/gromacs/2019.3/bin/gmx
# Data prefix:  /usr/local/bin/../Cellar/gromacs/2019.3
# Working dir:  /Users/gleb/Desktop/DO/unity_or_separation
# Command line:
# gmx cluster is part of G R O M A C S:
#
# Good gRace! Old Maple Actually Chews Slate
#
@    title "Cluster Sizes"
@    xaxis  label "Cluster #"
@    yaxis  label "# Structures"
@TYPE xy
@g0 type bar
       1       94
       2       31
       3       24
       4       24
       5       15
       6        6
       7        6
       8        5
       9        4
      10        4
      11        3
      12        3
      13        3
      14        3
      15        2
      16        2
      17        2
      18        2
      19        1
      20        1
      21        1
      22        1
      23        1
      24        1
      25        1

Answer 1

Just change ${file} to "$1" inside your function and it'd do what you want.

Also then consider changing this:

bar_xvg_proc () {
##AWK procession of XVG file: only for bar plot;
sed -i '' -e '/^[#@]/d' "$1"
# check XMAX and YMAX for each XVG
awk '
  NR==1{
    max1=$1
    max2=$2
  }
  $1>max1{max1=$1}
  $2>max2{max2=$2}
  END{printf "WORLD XMAX %s\nWORLD YMAX %s\n",max1+0.5,max2+0.5'} "$1" >> "${tmp}"/grace2.bfile

}

to this:

bar_xvg_proc () {
    ##AWK procession of XVG file: only for bar plot;
    # check XMAX and YMAX for each XVG
    awk '
      /^[#@]/ { next }
      (++nr)==1{
        max1=$1
        max2=$2
      }
      $1>max1{max1=$1}
      $2>max2{max2=$2}
      END{printf "WORLD XMAX %s\nWORLD YMAX %s\n",max1+0.5,max2+0.5'} "${@:--}" >> "${tmp}"/grace2.bfile
}

You never need sed when you're using awk and using "${@:--}" that way lets you have a function that will work whether you pass multiple file names to it or pipe a stream to it as it's telling awk to use stdin if no file is present.

Idk if you should really be using >> instead of > at the end of that, and you might want to do the output redirection outside of the function.