Multiple if within while loop ksh

UNIX for Beginners Q & A
1

Hi All,

I'm trying to write while loop with multiple if conditions. Each and every if condition with different variables. whenever one if condition fails i have remove the file
from filename and have to pick another file and loop should exit until the last file found in filename. Please help how to write a ksh shell script for that. Below i have given code what i tried

Thanks in advance.!!!

example:

#### here filename contain XXXX_YYYY_ZZZZ_DDD.txt as example
while read filename
#splitting a file without extension
full_filename=$filename
noextension=${full_filename%.*}
extension="${full_filename##*.}"

####assigning a patterns to different variable

echo "$noextension"|awk -F'_' '{ print NF-1 }' > countpattern

##### First fi######
if [ "$countpattern" -eq 5 ] ; then
A=$(echo $noextension|cut -d'_' -f1)
B=$(echo $noextension|cut -d'_' -f2)
C=$(echo $noextension|cut -d'_' -f3)
D=$(echo $noextension|cut -d'_' -f4)
E=$(echo $noextension|cut -d'_' -f5)
fi

####Second If########
if [ ! $extension=txt-a $A=HELP] || [ ! $extension=csv -a ! A =HELP ]
then
UPDATE TABLE ########################
rm full_filename
fi

####third if#####
if [ ! $C = "WE" ]
then
UPDATE TABLE ########################
rm full_filename
fi
2

How about

TMP=csvtxt                                                                     # extension template
while read filename
  do    IFS="._" read -A IARR <<< $filename                                    # split filename into array containing elements and extension (${IARR[-1]})
        if [ ! "${TMP/${IARR[-1]}}" = "$TMP" -a ! "${IARR[0]}" = "HELP" ] ||   # first condition  - former $A is ${IARR[0]} now
           [ ! "${IARR[2]}" = "WE" ]                                           # second condition
          then  # update table                                                 # do whatever necessary
                echo rm $filename                                              # remove echo to remove file
        fi
  done < input
3

${IARR[-1]} is bash-4.
ksh (and bash-3) need ${IARR[${#IARR[@]}-1]}

read -A and <<< require ksh93 - do not work with the older ksh88.

1 Like
4

ksh93+, (ksh was the shell the OP specified), also supports negative indexes, to indicate elements from right to left (probably after a certain revision level).
zsh also does this, but the first index of arrays is 1 , rather than 0 ..
bash requires version 4.3 or higher

1 Like
5

Here is one for all ksh versions:

#### here filename contain XXXX_YYYY_ZZZZ_DDD.txt as example
while read filename
do

### split filename on "."
extension="${filename##*.}"
[ "$extension" = "$filename" ] && extension=""
noextension=${filename%.*}
[ "$noextension" = "$filename" ] && noextension=""

### split noextension on "_" to AR[0] AR[1] ... AR[lenAR-1]
## ksh93 takes:
# IFS="_" read -A AR <<< "$noextension"
##
## ksh88 needs:
oIFS=$IFS
IFS="_"
set -f
set -A AR $noextension
IFS=$oIFS
set +f
##
lenAR=${#AR[@]}

### Conditions...
if
  [ "$extension" != "txt" -a "${AR[0]}" = "HELP" ] ||
  [ "$extension" != "csv" -a "${AR[0]}" != HELP ] ||
  [ "$ARR[2]" != "WE" ]
then
# UPDATE TABLE ########################
   echo rm "$filename"
fi

done

Remove the echo to run the rm command.