1) a function to check the free memory:
[admin@appsvr ~]$ function checkmem(){
> echo -n "The amount of free memeory is "
> free |head -2|tail -1|awk ‘{print $4}‘
> }
[admin@appsvr ~]$ checkmem
The amount of free memeory is 107940
2) using for loop to print the odd number from 1 to 99
for number in {1..99..2} do echo $number done
3) If and case
#!/bin/bash read X read Y if (( $X > $Y )); then printf "X is greater than Y" elif (( $X == $Y )); then printf "X is equal to Y" else printf "X is less than Y" fi #!/bin/bash read p case $p in Y|y) echo "YES" ;; N|n) echo "NO" ;; esac
4. delete the function name from terminal
[admin@appsvr ~]$ unset -f checkmem [admin@appsvr ~]$ checkmem bash: checkmem: command not found... [admin@appsvr ~]$
原文：https://www.cnblogs.com/amy2012/p/11627797.html