War Stories

aa c1
aa c2
aa c3
cc d1
dd e1
dd e2
ee f1

aa c1,c2,c3
cc d1
dd e1,e2
ee f1

first="Y"                
while read a b           
do                       
if [ "$first"  =  "Y"  ] 
then                     
   first="N"             
   prev=$a               
   echo "$a $b\c"        
else                     
if [ "$a" != "$prev" ]   
then                     
   echo "\n$a $b\c"      
   prev=$a               
else                     
   echo ",$b\c"          
fi                       
fi                       
done

for m in `cat ${input} | awk '{print $1}' | sort | uniq `
do
        var=`grep "^${m} " ${output} | awk '{print $2}' | tr '\n' ',' | sed '$s/,$//'`
        echo "${m} ${var}"
done

# Loop piping troubles.
#  This example by Anthony Richardson,
#+ with addendum by Wilbert Berendsen.


foundone=false
find $HOME -type f -atime +30 -size 100k |
while true
do
   read f
   echo "$f is over 100KB and has not been accessed in over 30 days"
   echo "Consider moving the file to archives."
   foundone=true
   # ------------------------------------
     echo "Subshell level = $BASH_SUBSHELL"
   # Subshell level = 1
   # Yes, we're inside a subshell.
   # ------------------------------------
done
   
#  foundone will always be false here since it is
#+ set to true inside a subshell
if [ $foundone = false ]
then
   echo "No files need archiving."
fi

# =====================Now, here is the correct way:=================

foundone=false
for f in $(find $HOME -type f -atime +30 -size 100k)  # No pipe here.
do
   echo "$f is over 100KB and has not been accessed in over 30 days"
   echo "Consider moving the file to archives."
   foundone=true
done
   
if [ $foundone = false ]
then
   echo "No files need archiving."
fi