/media/bill/PROJECTS/System_maintenance/Linux/for loops notes.txt
www.BillHowell.ca  23May2018 initial

see also "/media/bill/PROJECTS/System_maintenance/Linux/file read loops.txt"
+--+
from "$d_bin"'webPage scrape kyivindependent.sh'  
	kyivindependent_news()
{  
echo ""  >"$p_news"
if  [ -f  "$p_source" ]; then 
	old_date="old_date not set yet"
	while  read -u 9 line; do 
		new_date=$(  echo "$line"  |  grep '<div class="new-day">' |  sed  's|<div class=\"new-day\">\(.*\), \([a-zA-Z]\{3\}\)\(.*\) \([0-9]\+\)</div>|\4\22022|'  )  
		if  [ "$new_date" !=  "" ]; then 
			echo  "<B>$new_date</b><BR>" >>"$p_news"
			echo  "<BR>"	>>"$p_news"
			echo  ""			>>"$p_news"
			old_date="$new_date"
		fi
		inn_article=$(  echo "$line"  |  grep '<article id="post-'  )  
		if  [ "$inn_article" !=  "" ]; then 
			while  read -u 9 line; do 
				new_date=$(  echo "$line"  |  grep '<div class="new-day">' |  sed  's|<div class=\"new-day\">\(.*\), \([a-zA-Z]\{3\}\)\(.*\) \([0-9]\+\)</div>|\4\22022|'  )  
				if  [ "$new_date" !=  "" ]; then 
					echo  "<B>$new_date</b><BR>" >>"$p_news"
					echo  "<BR>"	>>"$p_news"
					echo  ""			>>"$p_news"
					old_date="$new_date"
				fi
				out_article=$(  echo "$line"  |  grep '<div class=\"clearfix\">'  )
				# Note: grep escape "-/ don't escape stuff within chr_apos
				new_time=$( echo "$line" |  grep '<span class="recent-date">'  |  sed  's|.*<span class="recent-date">\(.*\)</span>|\1|'  )
				if		[  "$new_time"  !=  ""  ]; then
						old_time="$new_time"
				fi
				link=$( echo "$line" |  grep '<a href="https://'  |  sed  's|[ ]\{2,\}||;s| rel=\"nofollow\" target=\"_blank\"||;s|</h3></div><div class="item">[ ]\+<h3 class="entry-title">|<BR>\n\n|;s|<div class=\"post\-thumb\">||;s|<div class=\"item\">||;s|<h3 class=\"entry\-title\">||;s| title=\".*\/">|\">|;s|</h3>||;s|</div>||;s|<a href=.*<img width=.*||' )
				content=$( echo "$line" |  grep '<span class="post-excerpt"><p>'  |  sed  's|\(.*\)<span class=\"post\-excerpt\"><p>\(.*\)<\/p>|\2|' )
				#echo "$content" 
				if		[ "$out_article" !=  "" ]; then 
						inn_article=""
						echo  "<BR>"			>>"$p_news"
						echo  ""					>>"$p_news"
				elif	[  "$link"	  !=  ""  ]; then 
						echo  "$old_time $old_date $link<BR>" 	>>"$p_news"
				elif	[  "$content" !=  ""  ]; then 
						echo  "$content<BR>" >>"$p_news"
				fi
			done
		fi
	done 9< "$p_source"  
else echo  "kyivindependent.com page source.txt doesnt exist : $p_source"
fi 
}  
************************************************************




08********08

https://www.shellhacks.com/bash-read-file-line-by-line-while-read-line-loop/

#] The general while read line construction that can be used in Bash scripts:
while read LINE
    do COMMAND
done < FILE
#!/bin/bash

#] FILE=$1
#] while read LINE; do
#]      echo "This is a line: $LINE"
#] done < "$FILE"




*************************
23May2018 for loops 

https://www.cyberciti.biz/faq/bash-for-loop/
Bash For Loop Examples
Posted on October 31, 2008in Categories BASH Shell, CentOS, Debian / Ubuntu, FreeBSD, Linux, Solaris-Unix, Suse, Ubuntu Linux, UNIX last updated December 25, 2017

Examples

#] This type of for loop is characterized by counting. The range is specified by a beginning (#1) and ending number (#5). The for loop executes a sequence of commands for each member in a list of items. A representative example in BASH is as follows to display welcome message 5 times with for loop:
#] 
#] #!/bin/bash
#] for i in 1 2 3 4 5
#] do
#]    echo "Welcome $i times"
#] done

#] Sometimes you may need to set a step value (allowing one to count by two’s or to count backwards for instance). Latest bash version 3.0+ has inbuilt support for setting up ranges:
#] 
#!/bin/bash
for i in {1..5}
do
   echo "Welcome $i times"
done
#] 
#] Bash v4.0+ has inbuilt support for setting up a step value using {START..END..INCREMENT} syntax:
#] #!/bin/bash
#] echo "Bash version ${BASH_VERSION}..."
#] for i in {0..10..2}
#] do 
#]    echo "Welcome $i times"
#] done


#] 
#] Three-expression bash for loops syntax - This type of for loop share a common heritage with the C programming language. It is characterized by a three-parameter loop control expression; consisting of an initializer (EXP1), a loop-test or condition (EXP2), and a counting expression (EXP3).

for (( EXP1; EXP2; EXP3 ))
do
	command1
	command2
	command3
done

A representative three-expression example in bash as follows:

#!/bin/bash
#] for (( c=1; c<=5; c++ ))
#] do  
#]    echo "Welcome $c times"
#] done

#] Conditional exit with break   You can do early exit with break statement inside the for loop. You can exit from within a FOR, WHILE or UNTIL loop using break. General break statement inside the for loop:

#] for I in 1 2 3 4 5
#] do
#]   statements1      #Executed for all values of ''I'', up to a disaster-condition if any.
#]   statements2
#]   if (disaster-condition)
#]   then
#] 	break       	   #Abandon the loop.
#]   fi
#]   statements3          #While good and, no disaster-condition.
#] done


#] 
#] Following shell script will go though all files stored in /etc directory. The for loop will be abandon when /etc/resolv.conf file found.

#!/bin/bash
#] for file in /etc/*
#] do
#] 	if [ "${file}" == "/etc/resolv.conf" ]
#] 	then
#] 		countNameservers=$(grep -c nameserver /etc/resolv.conf)
#] 		echo "Total  ${countNameservers} nameservers defined in ${file}"
#] 		break
#] 	fi
#] done

Early continuation with continue statement

To resume the next iteration of the enclosing FOR, WHILE or UNTIL loop use continue statement.

for I in 1 2 3 4 5
do
  statements1      #Executed for all values of ''I'', up to a disaster-condition if any.
  statements2
  if (condition)
  then
	continue   #Go to next iteration of I in the loop and skip statements3
  fi
  statements3
done

#] This script make backup of all file names specified on command line. If .bak file exists, it will skip the cp command.

#!/bin/bash
#] FILES="$@"
#] for f in $FILES
#] do
#]         # if .bak backup file exists, read next file
#] 	if [ -f ${f}.bak ]
#] 	then
#] 		echo "Skiping $f file..."
#] 		continue  # read next file and skip the cp command
#] 	fi
#]         # we are here means no backup file exists, just use cp command to copy file
#] 	/bin/cp $f $f.bak
#] done



# enddoc