1. Bash Shell Tips and Tricks
John, Mark, Brian, Michael, Ken, Lisa

2. Interactive shell puzzle 1
You just typed
$ ls –l policy.py stats.py ui_common.py
Count lines of the last file and make a .bak copy of it using
less than 20 keystrokes (no mouse, repeat key counts)

3. Interactive shell answer 1
You just typed
$ ls –l policy.py stats.py ui_common.py
Count lines of the last file and make a .bak copy of it using
less than 20 keystrokes (no mouse, repeat key counts):
$ wc !$
$ cp !$ !$.bak
or
$ cp !${,.bak}

4. Interactive shell puzzle 2
You just typed
$ ls –l policy.py rats.py ui_common.py
Correct rats.py to stats.py using 6 keystrokes (no mouse,
repeat key counts)

5. Interactive shell answer 2
You just typed
$ ls –l policy.py rats.py ui_common.py
Correct rats.py to stats.py using 6 keystrokes (no mouse,
repeat key counts):
$ ^r^st

6. Bash conditional
if [[ -d $x ]]
then
cd $x
make
cd ..
fi

7. Bash conditional - improved
if [[ -d “$x” ]]
then
( cd $x ; make )
fi

8. Bash conditional - alternate
[[ -d “$x” ]] &&
( cd $x ; make )

9. Bash iteration
for x in *.reclist
do
sort $x > $x.sorted
done

10. Bash iteration with break
for x in *.reclist
do
[[ -d “$x” ]] &&
break
sort $x > $x.sorted
done

11. Bash iteration - interactive
$ for x in *.reclist
> do
>
[[ -d “$x” ]] && break
>
sort $x > $x.sorted
> done

12. Bash variables
Default values
if [[ $i < ${max=100} ]] ...
Arithmetic
let n=2+2*3 n++ n*=3; echo $n
((n=(1+2))); echo $n  3
But
x=4; x+=6; echo $x  46
 27

13. Michael McKinnon’s trick
For Windows users, to dynamically change the
hover over value to reflect the machine you’re
logged into (eg, via Putty):
PROMPT_COMMAND=
'echo -ne "033]0;${USER}@${HOSTNAME%%.*}:${PWD/$HOME/~}007"'

14. Brian’s tricks
http://www.tldp.org/LDP/abs/html/
set –u exits on undefined variables
set –e exit immediately if a command exits with
a non-zero status
set –x echo commands before execution
use functions
pwd -P

15. Ken’s tricks
while read p; do
echo $p
done < peptides.txt
set –x; trap read debug