My personal 'collection' of short scripts (mostly Linux/Unix shell) that I may need to refer in the future…

Issue when creating CSV from spreadsheet program (e.g. Libreoffice Calc). The number string in column 3 of each line needs to be exactly 12 and the first line is a header line.

file=file.txt ; \
( head -n 1 $file ; \
tail -n +2 $file | \
while read line ; do \
line=${line// ,/,} ; \
test=$(echo $line|cut -d',' -f3) ; \
temp=$test ; \
while [ ${#test} -lt 12 ] ; do \
test="0$test" ; \
done ; \
line=${line//$temp/$test} ; \
echo "$line" ; \
done )

A script:

check_nrid.sh

#!/bin/bash
 
# check_nrid.sh
# - filters invalid nric in student list csv file for unidata
# - assume input is list.csv
# - run 'bash check_nric.sh list.csv >/dev/null' to check
# - if nothing comes out, then the file is good
# - run 'bash check_nrid.sh list.csv > list1.csv 2>/dev/null'
# - will get fixed data in list1.csv
 
check_nrid()
{
	local file loop line stid name nrid prog look prev
	file=$1
        [ ! -f $file ] && exit 0
	loop=0
	while read line ; do
		if [ $loop -gt 0 ] ; then
			stid=$(echo $line|cut -d',' -f1)
			name=$(echo $line|cut -d',' -f2)
			nrid=$(echo $line|cut -d',' -f3)
			prog=$(echo $line|cut -d',' -f4)
			look=0 prev=$nrid
			while [ ${#nrid} -ne 12 ] ; do
				nrid="0$nrid"
				look=1
			done
			# trim prog
			prog=${prog% }
			line="$stid,$name,$nrid,$prog,,,"
			if [ $look -ne 0 ] ; then
				echo "** [$prev] $line" >&2
			else
				echo "$line"
			fi
		fi
		((loop++))
	done < $file
}
check_nrid $@

while IFS="" read -r line || [ -n "$line" ] ; do
echo "> $line"
done <<< $(cat $file)

get_integer.sh

#!/bin/bash
get_integer()
{
	# use: get_integer <def_int> <var_int>
	local idef test temp
	idef=$1
	test=$2
	if [ ! -z $test ] ; then
		temp=$(echo "$test" | grep -E -v "^[0-9]*$")
		[ -z "$temp" ] && idef=$test
	fi
	echo -n "$idef"
}
[ "$(basename $0 sh)" = "get_integer" ] && get_integer $@

Find broken symbolic links in current path:

find $(pwd) -type l -exec test ! -e {} \; -print