Linux scripting

[Dont use]
for f in `cat file`; do
..
done

[use]
while read f; do
...
done file

[dont use]
grep | wc -l

[use]
grep -c 


[Dont use]
for f in `echo * or ls *`; do
command "$f"
done

[use]
for f in * ; do
command "$f"
done