for i in {1..10}; do echo | awk -v var=$i '{print var}' ; done
[oracle@stby ~]$ for i in {1..10}; do echo | awk -v var=$i '{print var}' ; done;
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
----------------------------------------------------------------------
$ a=55
$ a=55
$ b=87
$ echo $((a+b))
[oracle@stby ~]$ a=55
[oracle@stby ~]$ b=45
[oracle@stby ~]$
[oracle@stby ~]$ echo | awk -v var0=$a -v var1=$b '{print "division is: ", var1/var0}'
division is: 0.818182
to have division :-
============
[oracle@stby ~]$ printf "%.01f\n" $(echo "scale=1; 4/9" | bc)
0.4
[oracle@stby ~]$ printf "%.02f\n" $(echo "scale=1; 4/9" | bc)
0.40
[oracle@stby ~]$ printf "%.03f\n" $(echo "scale=1; 4/9" | bc)
0.400
[oracle@stby ~]$ printf "%.03f\n" $(echo "scale=3; 4/9" | bc)
0.444
[oracle@stby ~]$ printf "%.06f\n" $(echo "scale=6; 4/9" | bc)
0.444444
[oracle@stby ~]$ # %.0nf 👉"n"--- number of digits after decimal
[oracle@stby ~]$ # scale=6 👉 numbers of decimals digits can be calculated
1. unziping
unzip -o /path/to/source/*.zip -d /path/to/destination/
-o :- source
-d :- destination
2. cat file_name
3. strings binary_file
4. tar -cvzf backup.tar.gz --remove-files dir/
-cvzf :- create zip file
-xvzf :- extract zip file
--remove-files :- once the file archived it will then get deleted.
5. export day=Monday
unset day
6. date -d 'tomorrow'
date -d 'next week'
date -d 'next sun'
date -d 'next year'
date -d 'next month'
date -d 'next day'
date -d +'%r' for 12 hour timing
date -d +'%R' for 24 hour timing
date + %b ---> Sep
date + %B ---> September
date -d '+- days/months/years' +'%Y_%m_%d %H_%M_%s' ---> like 2023_09_04 09_05_45
7. to see shell
echo $SHELL
8. to do maths
echo $(( 5+5 ))
printf "%.0f\n" $(echo "scale=1; 2/5" | bc) --->
%.0f ---> 1
%.01f --> 1.0
%.02f --> 1.00
%.03f --> 1.000
i.e %.0nf ---> n means number of digits after decimal.
