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Useful K shell commands and examples






Description Command Example
How to get date in YYYYMMDDhhmmss format                         
date +%Y%m%d%H%M%S                                 date +%Y%m%d%H%M%S
20150701164849
      
How to get hostname uname -n
How to unzip and untar a file gunzip -c filename | tar -xvf -
How to check if a file is non zero size if [ -s file ]
How to check if a variable is empty  if [  -z file]
How to check if a directory is present if [  -d file]
How to check if a file is present if [  -f file]
How to extract file name from path  echo filename | sed -e's/.*\///' # echo "/opt/app/tmp/pom.xml" | sed -e's/.*\///'
pom.xml

How to zip a file  cat $file |  gzip -c > $FILENAME
How to retrieve return status from a shell $CTI/common/shells/SendToETL.sh TOPO $FILENAME
RC=$?
echo "Return status = $RC"

How to run a command on a remote server ssh -l user hostname '. ./.profile;echo $JAVA_HOME' ssh -l jm416b abc.com '. ./.profile;echo $JAVA_HOME'
How to view contents of a zip file zcat file.gz
How to retrieve result to an integer variable integer RESULT=$(wc -l $DIFFFILE | cut -d' ' -f1)
Numeric comparison if [ $RESULT -gt 0 ] you can also use -gt,-ge,-le,-lt,-eq,-ne
String comparison if [ "$HLCS" != "" ] use = =  for equality
Convert uppercase to lowercase DNS=$(echo "$DNS" | tr '[A-Z]' '[a-z]'
Convert lowercase to uppercase DNS=$(echo "$DNS" | tr '[a-z]' '[A-Z]'
A file is newer than another if [[ FILE1 -nt FILE2 ]];                  then echo FILE1 is newer than FILE2
fi

A file is older than another if [[ FILE1 -nt FILE2 ]];                  then echo FILE1 is newer than FILE2
fi







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