linux - In 'grep' - Why does it behave this way? -

file still contains:

a b c d

and

grep -v -e "a" -e "d" still

gives:

b c

which expected.

now, file fill contains:

a,b,c,d

my command

grep -v -e "a" -e "d" fill

i expected give me ,b,c,. but, no output. why ?

first of all, first example should give :

b c

not

b d

because have -v

your 2nd attempt gave nothing, because grep match line-wise. if whole line doesn't match, line won't in output.

if want remove a , d in 2nd example, use sed:

kent$  echo "a,b,c,d"|sed 's/[ad]//g' ,b,c,

Sher