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How to check if there is only one row in the file?

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# 1  
Old 10-05-2010
How to check if there is only one row in the file?

How can I check if there is only one row in the file? If there are more than one rows, I need to send an email and if there is only one row, do not do anything.

Thanks in anticipation
# 2  
Old 10-05-2010
if [ "`wc -l <file> | awk '{ print $1 }'`" -ne 1 ]; then
   echo "longer...." | mail -s "subject"

# 3  
Old 10-05-2010
While "wc -l <file" prints "1", you can save a fork and exec with this:


exec <$1

read ln
read ln
if [ "$ln" != "" ]
 echo "longer...." | mail -s "subject"

# 4  
Old 10-05-2010
$ ruby -ne 'BEGIN{c=0};c+=1 if $_ !~ /^[[:space:]]+$/; (`echo "long" | mail -s "long" root`;exit) if c==2 ' file

# 5  
Old 10-06-2010
awk 'END{print (NR>1)?"wrong":X}' infile

# 6  
Old 10-06-2010
Solutions that count all the lines are wasting a lot of time, for big files.


sed '
 ' file_in | read zans

if [ "$zans" = "Longer" ]
 echo "File grew." | mailx -s "File grew"

# 7  
Old 10-06-2010
Originally Posted by DGPickett
Solutions that count all the lines are wasting a lot of time, for big files.
awk 'NR-1{print "File grew."; exit}' infile | mailx -s "File grew"


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