[SLUG] useful bash tricks thread

[Tony Sceats <tony@xxxxxxxxxxx>]

It's been a while since there's been a thread like this, so I thought it
would be fun :)

so, have you got any?

I've got 2 to share today:

alt >and then
alt <

for interactive shells, works kinda like ctrl r or !$ - that is, it searches
your history but in a strangely useful but different way

-and-

built-in bash substitution, handy for decimal comparison (iff your decimal
precisions are the same)

tony@hermies:~$ VALUE=2.05
tony@hermies:~$ echo $VALUE
2.05
tony@hermies:~$ echo ${VALUE/./}
205
tony@hermies:~$ if [ ${VALUE/./} -gt 200 ] ; then echo $VALUE greater than
2;fi
2.05 greater than 2

and as you can see the substitution works for any chars, not just .

tony@hermies:~$ echo ${VALUE/2/4}
4.05

so there's no need to exec sed for simple stuff :)