Some useful Unix commands for shell scripting

IF-ELSE

if [ "$value" -eq "0" ] || [ "$value" -ge "2" ]; then
    echo "condition met"
else
    echo "condition not met"

fi

Comparisons:

-eq	equal to
-ne	not equal to
-lt	less than
-le	less than or equal to
-gt	greater than
-ge	greater than or equal to

Exit Host concurrent program with Error

exit 2;

 Linux Find and Move Archive files older than N days

find $frompath -type f -mtime +$age -exec mv {} $archive \;

Obtain value from string

echo $value | cut -f1 -d"."

Command will return the value starting to until “.” is found.

Test.txt will return Test

Using SUBSTR in Unix

echo $name | awk '{ print substr( $0, 0, length($0)-4 ) }'

Command will return name starting from 0 to (lengthofstring)-4

Test.txt will return Test