Ignoring characters at start and end of words

Question

I'm trying to pass a flatdb with some names through a script in order to ignore certain things fields and check others. Currently this is as far as I've gotten.

What would I use in my then statement in order to ignore the comment and space lines?

EDIT: Sample of file being read

Bob,Brown,Smith,39
#Alex,Jay,Jones,83
Justin,Michael,White,18
 James,Paul,Weis,54

EDIT: Then I am separating each name

IFS_SAVE=${IFS}
IFS=,
while read value1 value2 value3 value4
do
 echo "First name ${value1}"
 echo "Middle name ${value2}"
 echo "Last name ${value3}"
 echo "Age ${value4}"
done < ${1}

Then I'm trying to ignore blank lines in the file

while read value1 value2 value3 value4
do
if [ -z ${value1} ]
 then
   echo "blank line exists"
 fi
done < ${1}

Then I'm trying ignore commented lines in file

while read value1 value2 value3 value4
do
if [ "${value1:0:1}" = "#" ]
 then
    echo "comment exists"
 fi
done < ${1}

From here down I have been unable to get this to actually work

I'm trying to check if fields start or end with space

while read value1 value2 value3 value4
do
if [[ ${value1} = *[[:space:]]* ]]
then
    echo "space exist"
fi
done < ${1}

EDIT: Ideal output

First name Bob
Middle name Brown
Last name Smith
Age 39
First name Justin
Middle name Michael
Last name White
Age 39
 James,Paul,Wise,54 space exist

Answer 1

Use a text processing tool to process text, not hundreds of invocations of inappropriate tools such as read or echo in a loop.

Here, the obvious one to process tabular data is awk:

awk -F, -v OFS='\n' '
  ! /^[#[:space:]]/ {
    print "First name "  $1, \
          "Middle name " $2, \
          "Last name "   $3, \
          "Age "         $4
  }' < you-file

The ! /^[#[:space:]]/ condition matches on lines that don't (!) start (^) with # or whitespace character. You could also do /^[^#[:space:]]/ to match on lines that start with a character other than # or whitespace which in effect would also skip empty lines or add && NF == 4 to skip the lines that don't have exactly 4 fields.

Or to pass the lines with leading or trailing whitespace along untouched as in your expected output:

awk -F, -v OFS='\n' '
  /^[[:space:]]/ || /[[:space:]]$/ {print; next}
/^[^#]/ && NF == 4 {
    print "First name "  $1, 

          "Middle name " $2, 

          "Last name "   $3, 

          "Age "         $4
  }' < you-file

(Here, we're assuming a POSIX compliant awk; with mawk, replace [:space:] with the hardcoded list of whitespace characters you expect to find at the start as mawk doesn't support POSIX character classes).

Also beware that the carriage return character (aka CR / \r / ^M) is considered a [:space:] character. If the input file was a text file coming from Microsoft OSes, where the line delimiter is CRLF instead of just LF in Unix, then each line would end in a whitespace character. You'd want to run the file through dos2unix first to convert it to Unix format.

Answer 2

Since word-splitting happens over IFS and default IFS consists of 'tab/space/newline' and you need to set the IFS to a comma ,, so you would need:

while IFS=, read -r  …

and also change ${value1} = *[[:space:]]* to "${value1}" =~ ^[[:space:]] to pattern-matching that starts with whitespace; and there is no real word meaning it's just how IFS splits on (here it's a single comma).

see also Why is using a shell loop to process text considered bad practice?