ืึทืืึธื, ืืขืฉืึทืก ืึทื ืืื ืืขืจืืืื, ืืื ืืื ืืขืืืขื ืืขืคืจืขืื, ืืืึธืก ืืืขื ืืืจ ืืึธื ืืืื ืืืจ ืืขืคึฟืื ืขื ืึท ืืื ืกื ื ืืฉื ืืจืืขืื ืจืขืื ืฆื ืืขื ืคืึทืงื ืึทื ืืขืจ ืืืกืง ืืื ืืืืคื ืืืืก ืคืื ืคึผืืึทืฅ?
ืคืืจืฉืืฒ ื ืืื , ื ื ืื ื ืฐืข ื ืืขื , ืฐื ืก ืื ื ืคืืจื ืืืข ื ืคื ื ืืข ื ืืจื , ืื ื ืืื ื ืืขืืืข ื ืฐืข ื ืื ื ืจืฒื ืืง ื ืื ื ืืจื .
ืืขืจื ืึธื ืืึธื ืืขืจ ืืื ืืขืจืืืืืขืจ ืืขืคืจืขืื, ืืืึธืก ืืืื ืขืก ืืื ืงืืื ืคืจืื ืคึผืืึทืฅ ืืืืฃ ืืขืจ ืฆืขืืืืืื ื, ืึธืืขืจ ืืืจ ืืืื ืืึธื ื ืื ืืขื ืงืืื ืืขืงืขืก ืืืึธืก ืืืึธืื ื ืขืืขื ืึทืืข ืื ืคึผืืึทืฅ?
ืฆื ืืขื ืืื ืืขืืืื ืึทื ืืืจ ืงืขื ืขื ืฉืืขื ืืืง ืงืืงื ืืื ืขืคืขื ืขื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก, ืคึฟืึทืจ ืืืึทืฉืคึผืื ืืื ืื lsof ืืึทืคึฟืขื, ืืื ืคึฟืึทืจืฉืืืื ืืืึธืก ืึทืคึผืืึทืงืืืฉืึทื ืืื ืืขื ืืืขื ืึทืืข ืื ืื ืืืฆื ืคึผืืึทืฅ, ืืื ืืืจ ืงืขื ืขื ืืึทื ืืืขื ืืืื ืื ืฆืืฉืืื ืื, ืืืคึผืขื ืืื ื ืืืืฃ ืฆื ืื ืืึทืื ืืขื ืขื ืืืจืฃ .
ืืขืจ ืื ืืขืจืืืืืืขืจ ืื ืืขืจืึทืคึผืืื ืืืจ ืืืืฃ ืื ืืขืฆืืข ืืืึธืจื, ืึทืืื ื ืฆื ืืืื ืงืฉืื: "ืจืขืื ืืืจ ืืึธื ื ืื ืืึทืจืคึฟื ืื ืืึทืื, ืขืก ืืื ื ืึธืจ ืึท ืืืืึทื ืงืืึธืฅ, ืึธืืขืจ ืื ืึทืคึผืืึทืงืืืฉืึทื ืืื ื ืืฉื ืึทืจืืขืื ืืืืึทื ืขืก ืงืขื ื ืืฉื ืฉืจืืึทืื ืึท ืืืืึทื"?
"ืึธืืงืื," ืืื ืืขืขื ืืคืขืจื, "ืืืจ ืงืขื ืขื ืงืขืจ ืึทืืืขืง ืืืืึทื ืืื ืื ืึทืคึผืืึทืงืืืฉืึทื ืงืึทื ืคืืืืขืจืืืฉืึทื ืืื ืจืืกืืึทืจื ืขืก."
ืืขืจ ืืื ืืขืจืืืืืขืจ ืืึธื ืึทืืืืฉืขืงืืื: "ื ืืื, ืืืจ ืงืขื ืขื ื ืืฉื ืจืืกืืึทืจื ืื ืึทืคึผืืึทืงืืืฉืึทื, ืืืจ ื ืึธื ืืึธืื ืืืืืืืง ืืึทืื ืกืืึธืจื ืืื ืืึผืจืื, ืืื ืืืืืืืง ืงืืืืึทื ืฅ ืืขื ืขื ืงืึธื ื ืขืงืืขื ืฆื ืื ืกืขืจืืืืก ืืื, ืืืึธืก ืืืจ ืงืขื ืขื ื ืืฉื ืฆืืืื ืืขื ืืื ืืืืืขืจ ืฆื ืคืึทืจืืื ืื."
"ืึธืืงืื," ืืื ืืขืืืื, "ืืืื ืืืจ ืงืขื ืขื ื ืืฉื ืจืืกืืึทืจื ืื ืึทืคึผืืึทืงืืืฉืึทื ืืื ืื ืืึทืื ืืขื ืขื ื ืืฉื ืืืืืืืง ืคึฟืึทืจ ืืื ืื, ืืืจ ืงืขื ืขื ืคืฉืื ืืืกืืขืงื ืืขื ืึธืคึฟื ืืขืงืข ืืืจื ืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ, ืืคืืื ืืืื ืืืจ ืืึธื ื ืื ืืขื ืขืก ืืื ืื ls ืืึทืคึฟืขื. ืืืืฃ ืืขืจ ืืขืงืข ืกืืกืืขื."
ืืขืจ ืืื ืืขืจืืืืืขืจ ืืื ืืขืืืขื ืฆืืคืจืืื, ืึธืืขืจ ืืื ื ืืฉื.
ืืขืจื ืึธื ืืึธื ืืื ืืขืืจืึทืื, ืคืึทืจืืืึธืก ืืจืึธืื ืืขืจ ืืขื ืืฉ ืืืึธืก ืืขืกื ืืืื ืืืืกื ื ืืฉื ืืืคืขืจ? ืึธืืขืจ ืืืึธืก ืืืื ืื ืืึทืื ืืขื ืขื ื ืึธื ืืืืืืืง? ืืืึธืก ืืืื ืืืจ ืงืขื ืขื ื ืืฉื ืจืืกืืึทืจื ืึท ืคึผืจืึธืฆืขืก, ืืื ืืขืจ ืคึผืจืึธืฆืขืก ืฉืจืืืื ืฆื ืื ืืขืงืข ืกืืกืืขื ืืืืฃ ืึท ืฆืขืืืืืื ื ืืืึธืก ืืื ืงืืื ืคืจืื ืคึผืืึทืฅ? ืืืึธืก ืืืื ืืืจ ืงืขื ืขื ื ืืฉื ืคืึทืจืืืจื ื ืื ืืืืื ืื ืืึทืื ืืืึธืก ืืื ืฉืืื ืืขืฉืจืืื, ืึธืืขืจ ืืืื ืื ืืึทืื ืืืึธืก ืืขืจ ืคึผืจืึธืฆืขืก ืฉืจืืืื ืึธืืขืจ ืคืจืืืื ืฆื ืฉืจืืึทืื?
ืืืืืง
ืคืจื ืืื ืืืื ืงืึทืจืืขืจืข, ืืื ืืขืคืจืืืื ืฆื ืฉืึทืคึฟื ืึท ืงืืืื ืึทืคึผืืึทืงืืืฉืึทื ืึทื ืืืจืฃ ืฆื ืงืจืึธื ืืึทื ืืฆืขืจ ืืื ืคึฟืึธืจืืึทืฆืืข. ืืื ืืขืืึธืื ืืื ืืขืืึทื ืง, ืืื ืงืขื ืขื ืืื ืืืืึทืื ืืขื ืืึทื ืืฆืขืจ ืฆื ืืืื ืืึทืื. ืคึฟืึทืจ ืืืึทืฉืคึผืื, ืืื ืืึธืื ืืืืึทื ืึธืื ืืืืืื ืืืืืื ืึธืืืืืฉ, ืืื ืขืจ ืืื ืขืืืขืืข ืืื ืคึฟืึธืจืืึทืฆืืข, ืึธืืขืจ ืืื ืงืขื ืขื ืืื ืืึทืื ืคืจืืื ื ืืื ืืื? ืืื ืงืขื ืืืืื ืึธื ืืืืึทืื ืึทื ืืขืจ ืืื ื ืืืื ื ืึธืืขื "ืืืืืง" ืืขืืขืจื ืฆื ืืขื ืืืืขืจ ืืืืืื. ืืืขืจ ืืืึธืก ืืืื ืขืจ ืืืืฉื ืืืื ื ืึธืืขื ืืื ืึทื ืฉืืึธื ืคืื ืืืืืื ืืืขืจื, ืืืฉื, ืึธืืืึท? ืืขืืื ื ืฐืข ื ืื ื ืืืืกืฐืฒืืขื , ื ื ืืื ืืข ืจ ืืืืื ื ืืืฐืื ืืฐืข ืจ ืืืฐืื ืืฐื , ืฐืข ื ืฉืื ื ื ืืฉ ื ืืื ื ืงืฒ ื ืืื ื , ืื ื ืืื ืืืข ืจ ืืืื ืง ืฐืข ื ื ื ื ืืขืืขืจ ื ืฆ ื ืืข ื ื ืืึพืขืงืืืกืืืจืขื ืข ื ืืืืืื . ื ืืึทืืึทืืืืก ืืืึธืก ืืึธื ืืขืืขืื ืืขืื ืืื ืืฆืขืจ ืึทื ืืืืื ืึทืจืืืงื ืืืืขื ืืืคืืฆืืจื (ืืืื) ืืึธื ืืขืืึธืืคื ืืืืื ืืขื ืคืจืืืืขื, ืืื ืืืื ืืืืืง ืืื ืืขืืืขื ืฆืืืขืืื ืื ืืื ืืขื ID, ืืืึธืก ืืื, ืืื ืคืึทืงื, ื ืึธืจ ืึท ืกืืจืืึทื ื ืืืขืจ. ืืืื, ืื ืืึทืืืฆืขืจ ืคืื ืื ืืืื ืืื ืฉืืึทื ื ืืืขืจ 2, ืืื ืืื ืขืืืขืืข ืคืื ื ืืื ืฆืืึทื ืืืืืื ืืื ืืขืืืขื ืืื ืืขืจ ืืขื ืฉืืึทื, ืืื ืืขืืึธืื ืึธืืืึท ืืขืืืืจื ืืื ืืขืจ ืืขืจ ืืขืืืืงืขืจ ืฉืืึทื. ืื ืคึผืจืึธืืืขื ืคืื ืืขื ืืฉืืืึทื ืืื ืืืึทืข ืืึทืืืึทื ื ืืื ืคึผืจืึทืงืืึทืงืื ืกืึทืืืื.
ืืขืงืข ืืืกืงืจืืคึผืืึธืจ
ืืขืจ ืคึผืจืึธืืืขื ืคืื ืืขืจ ืืขืงืข ืืื ืื ืคึผืจืึธืืจืึทื ืืืึธืก ืึทืจืืขื ืืื ืืขื ืืขืงืข ืืื ืืขืขืจืขื ืืขืจ ืืขืืืืงืขืจ ืืื ืึทื ืคืื ืืื ืืืขืจ ืืื ื ืืื ืืขื ืืฉ. ืจืขืื ืืื ืืขืขืคื ื ืึท ืืขืงืข ืืขืจืืคื ivan.txt ืืื ืื ืืขืืืืื ืฆื ืฉืจืืึทืื ืื ืืืึธืจื tuzik ืืื ืขืก, ืึธืืขืจ ื ืึธืจ ืืขืจืืื ืฆื ืฉืจืืึทืื ืืขืจ ืขืจืฉืืขืจ ืืจืืื "ื" ืืื ืืขืจ ืืขืงืข, ืืื ืืขื ืืขืงืข ืืื ืจืื ืืืื ืืืจื ืขืืขืฆืขืจ, ืืืฉื, ืฆื olya.txt. ืืืขืจ ืื ืืขืงืข ืืืืืื ืื ืืขืืืข, ืืื ืืื ื ืึธื ืืืืื ืฆื ืจืขืงืึธืจืืืจื ืืืื ืืืื ืืื ืขืก. ืืขืืขืจ ืืึธื ืึท ืืขืงืข ืืื ืึธืคึผืขื ืขื ืืืจื ืึท ืกืืกืืขื ืจืืคื ืืื ืงืืื ืคึผืจืึธืืจืึทืืืื ื ืฉืคึผืจืึทื ืืื ืืึทืงืืืขื ืึท ืืื ืฆืืง ืฉืืึทื ืืืึธืก ืืืืืื ืืืจ ืฆื ืึท ืืขืงืข, ืืขื ืฉืืึทื ืืื ืืขืจ ืืขืงืข ืืืกืงืจืืคึผืืึธืจ. ืืื ืก'ืืื ืืืื ื ืืฉื ืงืืื ืืืืืง ืืืืก ืืื ืืืขืจ ืืื ืืื ืืขื ืืขืงืข ืืืืืืขืจ, ืืขื ืงืขื ืขืก ืืืืกืืขืงื, ืืขื ืงืขื ืขืก ืืืืฉื ื ืืืขื, ืืืืฉื ืืขื ืืขื ืืืืช, ืืืขืจ ืืขื ืงืขื ืืืืขืงื ืขืืขื ืื ืจืขืื ืฆื ืืืืขื ืขื ืืื ืฉืจืืืื, ืืื ืืืขื ื ืื ืืืื ืฆืืืจืื ืฆื ืืื, ืืืืื ืืื ืืขืจ ืฆืืื ืคืื ืขืคื ืื ืคืืื, ืืื ืืื ืืขืืื ืื ืจืขืื ืขืก ืฆื ืืืื ืขื ืืื/ืืืขืจ ืฉืจืืืื ืืื ืืื ืืื ืืขืืื ืื ืื ืฆืืืืืื ืืจืืขืื ืืื ืืื, ืืืก ืืืื ื ืื ืืื ืืื ืืืื ืืืืืืขืจ ืืื.
ืืื ืืื ืืงืก, ืื ืืืืง ืืืืืืึธืืขืง ืึธืคึผืขื ืก 3 ืืืกืงืจืืคึผืืึธืจ ืืขืงืขืก ืคึฟืึทืจ ืืขืืขืจ ืคืืืกื ืืืง ืึทืคึผืืึทืงืืืฉืึทื (ืคึผืจืึธืกืขืก), ืืขืฆืืืื 0,1,2. ืืขืจ ืืื ืคึฟืึธืจืืึทืฆืืข ืงืขื ืขื ืืืื ืืขืคึฟืื ืขื ืืืืฃ ืื ืืื ืงืก ะธ
- ืืขืงืข ืืืกืงืจืืคึผืืึธืจ 0 ืืื ืืขืจืืคื STDIN ืืื ืืื ืคืืจืืื ืื ืืื ืึทืคึผืืึทืงืืืฉืึทื ืึทืจืืึทื ืฉืจืืึทื
- ืืขืงืข ืืขืกืงืจืืคึผืืึธืจ 1 ืืื ืืขืจืืคื STDOUT ืืื ืืื ืืขื ืืฆื ืืืจื ืึทืคึผืืึทืงืืืฉืึทื ื ืฆื ืจืขืืืืืึทื ืืึทืื, ืึทืืึท ืืื ืืจืืง ืงืึทืืึทื ืื
- ืืขืงืข ืืขืกืงืจืืคึผืืึธืจ 2 ืืื ืืขืจืืคื STDERR ืืื ืืื ืืขื ืืฆื ืืืจื ืึทืคึผืืึทืงืืืฉืึทื ื ืฆื ืจืขืืืืืึทื ืืขืืช ืึทืจืืืงืืขื.
ืืืื ืืื ืืืื ืคึผืจืึธืืจืึทื ืืืจ ืขืคืขื ืขื ืงืืื ืืขืงืข ืคึฟืึทืจ ืืืืขื ืขื ืึธืืขืจ ืฉืจืืืื, ืจืืึฟ ืืกืชึผืื ืืืจ ืืืขื ืืึทืงืืืขื ืืขืจ ืขืจืฉืืขืจ ืคืจืื ืฉืืึทื ืืื ืขืก ืืืขื ืืืื ื ืืืขืจ 3.
ืื ืจืฉืืื ืคืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืงืขื ืขื ืืืื ืืืืื ืคึฟืึทืจ ืงืืื ืคึผืจืึธืฆืขืก ืืืื ืืืจ ืืืืกื ืืืึทื PID.
ืคึฟืึทืจ ืืืึทืฉืคึผืื, ืืึธืื ืืื ืื ืขืคืขื ืขื ืื ืืึทืฉ ืงืึทื ืกืึธืื ืืื ืงืืง ืืื ืื PID ืคืื ืืื ืืืขืจ ืคึผืจืึธืฆืขืก
[user@localhost ]$ echo $$
15771
ืืื ืื ืจืืข ืงืึทื ืกืึธืื ืืึธืื ืืื ืื ืืืืคื
[user@localhost ]$ ls -lah /proc/15771/fd/
total 0
dr-x------ 2 user user 0 Oct 7 15:42 .
dr-xr-xr-x 9 user user 0 Oct 7 15:42 ..
lrwx------ 1 user user 64 Oct 7 15:42 0 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 2 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 255 -> /dev/pts/21
ืืืจ ืงืขื ืขื ืืขืฉืึธืืขื ืืืื ืึธืจืืจื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ื ืืืขืจ 255 ืคึฟืึทืจ ืื ืฆืืืขืงื ืคืื ืืขื ืึทืจืืืงื; ืขืก ืืื ืืขืืืขื ืขืคื ืคึฟืึทืจ ืืืึทื ืืืืขืจืคืขื ืืฉื ืืืจื ืืึทืฉ ืืื, ืืื ื ืืฉื ืืืจื ืื ืืื ืืงื ืืืืืืึธืืขืง.
ืืืฆื ืึทืืข 3 ืืืกืงืจืืคึผืืึธืจ ืืขืงืขืก ืืขื ืขื ืคืืจืืื ืื ืืื ืื ืคึผืกืขืืืืึธ ืืืึธืงืืึทื ืืืื , ืึธืืขืจ ืืืจ ืงืขื ืขื ื ืึธื ืืึทื ืืคึผืืืืจื ืืื, ืคึฟืึทืจ ืืืึทืฉืคึผืื, ืืืืคื ืืื ืืื ืึท ืฆืืืืื ืงืึทื ืกืึธืื
[user@localhost ]$ echo "hello world" > /proc/15771/fd/0
ืืื ืืื ืืขืจ ืขืจืฉืืขืจ ืงืึทื ืกืึธืื ืืืจ ืืืขืื ืืขื
[user@localhost ]$ hello world
ืจืืืขืจืขืงื ืืื ืจืขืจ
ืืืจ ืงืขื ืขื ืืืืื ืึธืืืืขืจืจืืื ืื 3 ืืืกืงืจืืคึผืืึธืจ ืืขืงืขืก ืืื ืงืืื ืคึผืจืึธืฆืขืก, ืึทืจืืึทื ืืขืจืขืื ื ืืื ืืึทืฉ, ืืืฉื ืืืจื ืึท ืจืขืจ ืงืึทื ืขืงืืื ื ืฆืืืื ืคึผืจืึทืกืขืกืึทื, ืืขื
[user@localhost ]$ cat /dev/zero | sleep 10000
ืืืจ ืงืขื ืขื ืืืืคื ืืขื ืืึทืคึฟืขื ืืื ืืื strace -f ืืื ืืขื ืืืืก ืขืก ืืื ืืื ืืื ืขืืืืื ืื, ืืืขืจ ืืื ืืืขื ืืืจ ืืืื ืืงืืฆืืจ.
ืืื ืืืขืจ ืคืึธืืขืจ ืืึทืฉ ืคึผืจืึธืฆืขืก ืืื PID 15771 ืคึผืึทืจืกืขืก ืืื ืืืขืจ ืืึทืคึฟืขื ืืื ืคึฟืึทืจืฉืืืื ืคึผืื ืงื ืืื ืคืืืข ืงืึทืืึทื ืื ืืืจ ืืืืื ืฆื ืืืืคื, ืืื ืืื ืืืขืจ ืคืึทื ืขืก ืืขื ืขื ืฆืืืื ืคืื ืืื: ืงืึทืฅ ืืื ืฉืืึธืคื. ืืึทืฉ ืืืืืกื ืึทื ืขืก ืืึทืจืฃ ืฆื ืฉืึทืคึฟื ืฆืืืื ืงืื ื ืคึผืจืึทืกืขืกืึทื, ืืื ืฆืื ืืืคืืืกื ืืื ืืื ืืืื ืจืขืจ. ืืื ืืึทื ืฅ, ืืึทืฉ ืืืขื ืืึทืจืคึฟื 2 ืงืื ื ืคึผืจืึทืกืขืกืึทื ืืื ืืืื ืจืขืจ.
Bash ืืืืคื ืึท ืกืืกืืขื ืจืืคื ืืืืืขืจ ืงืจืืืืืื ื ืงืื ื ืคึผืจืึทืกืขืกืึทื ืืื ืืืงืืื ื ืืึท ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืืืืฃ ืื ืฆืืึทืืืืืึทืืืง ืจืขืจ ืืึทืคืขืจ, ืึธืืขืจ ืืขื ืืึทืคืขืจ ืืื ื ืืฉื ื ืึธื ืคืึทืจืืื ืื ืืื ืืืขืจ ืฆืืืื ืงืื ื ืคึผืจืึทืกืขืกืึทื.
ืคึฟืึทืจ ืื ืคืึธืืขืจ ืคึผืจืึธืฆืขืก, ืขืก ืงืืงื ืืื ืขืก ืืื ืฉืืื ืึท ืจืขืจ, ืึธืืขืจ ืขืก ืืขื ืขื ื ืึธื ืงืืื ืงืื ื ืคึผืจืึทืกืขืกืึทื:
PID command
15771 bash
lrwx------ 1 user user 64 Oct 7 15:42 0 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 2 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 3 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:42 4 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:42 255 -> /dev/pts/21
ืืขืจื ืึธื ื ืืฆื ืื ืกืืกืืขื ืจืืคื bash ืงืจืืืืฅ ืฆืืืื ืงืื ื ืคึผืจืึทืกืขืกืึทื, ืืื ืืื ืืืขืจ ืืจืื ืคึผืจืึทืกืขืกืึทื ืืืขืื ืงืืงื ืืื ืืึธืก:
PID command
15771 bash
lrwx------ 1 user user 64 Oct 7 15:42 0 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 2 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 3 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:42 4 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:42 255 -> /dev/pts/21
PID command
9004 bash
lrwx------ 1 user user 64 Oct 7 15:57 0 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 2 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 3 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:57 4 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:57 255 -> /dev/pts/21
PID command
9005 bash
lrwx------ 1 user user 64 Oct 7 15:57 0 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 2 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 3 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:57 4 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:57 255 -> /dev/pts/21
ืื ืืืืกื ื ืืฉื ืคืึทืจืืขืกื ืึทื ืงืืึธืื ืงืืึธืื ื ืืขื ืคึผืจืึธืฆืขืก ืฆืืืืืขื ืืื ืึทืืข ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก, ืึทืืื ืืื ืืืขืื ืืืื ืื ืืขืืืข ืืื ืื ืคืึธืืขืจ ืคึผืจืึธืฆืขืก ืืื ืืื ืื ืงืื ื. ืืขืจ ืึทืจืืขื ืคืื ืืขืจ ืคืึธืืขืจ ืคึผืจืึธืฆืขืก ืืื PID 15771 ืืื ืฆื ืืึธื ืืืึธืจ ืื ืงืื ื ืคึผืจืึทืกืขืกืึทื, ืึทืืื ืขืก ื ืึธืจ ืืืืจืื ืคึฟืึทืจ ืึท ืขื ืืคืขืจ ืคืื ืื ืงืื ืืขืจ.
ืืขืจืืืขืจ, ืขืก ืืื ื ืืฉื ืืึทืจืคึฟื ืจืขืจ, ืืื ืขืก ืงืืึธืืืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืืขืฆืืืื 3 ืืื 4.
ืืื ืืขืจ ืขืจืฉืืขืจ ืงืื ื ืืึทืฉ ืคึผืจืึธืฆืขืก ืืื PID 9004, ืื ืกืืกืืขื ืจืืคื , ืขื ืืขืจืื ืืขื ืืื ืืืขืจ STDOUT ืืขืงืข ืืขืกืงืจืืคึผืืึธืจ ื ืืืขืจ 1 ืฆื ืึท ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ืืืึธืก ืืืืืื ืฆื ืจืขืจ, ืืื ืืื ืืืขืจ ืคืึทื ืขืก ืืื ื ืืืขืจ 3. ืึทืืื ืึทืืฅ ืืืึธืก ืืขืจ ืขืจืฉืืขืจ ืงืื ื ืคึผืจืึธืฆืขืก ืืื PID 9004 ืฉืจืืืื ืฆื STDOUT ืืืขื ืืืืืึธืืึทืืืฉ ืขื ืืืงื ืืื ืื ืจืขืจ ืืึทืคืขืจ.
ืืื ืื ืฆืืืืืืข ืงืื ื ืคึผืจืึธืฆืขืก ืืื PID 9005, ืืึทืฉ ื ืืฆื ืืืคึผ2 ืฆื ืืืืฉื ืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ STDIN ื ืืืขืจ 0. ืืืฆื ืึทืืฅ ืืืึธืก ืืื ืืืขืจ ืฆืืืืืืข ืืึทืฉ ืืื PID 9005 ืืืขื ืืืืขื ืขื ืืืขื ืืืื ืืืืขื ืขื ืคืื ืื ืจืขืจ.
ื ืึธื ืืขื, ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืืขืฆืืืื 3 ืืื 4 ืืขื ืขื ืืืื ืคึฟืึทืจืืึทืื ืืื ืื ืงืื ื ืคึผืจืึทืกืขืกืึทื, ืืืืึทื ืืื ืืขื ืขื ื ืื ืืขืจ ืืขื ืืฆื.
ืืื ืืืืืืจืึทืืื ืืืื ืึธืจืืจื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ 255; ืขืก ืืื ืืขื ืืฆื ืคึฟืึทืจ ืื ืขืจืืขื ืฆืืืขืงื ืืืจื ืืึทืฉ ืืื ืืื ืืืขื ืืืื ืืืื ืคืืจืืืื ืืื ืงืื ื ืคึผืจืึทืกืขืกืึทื.
ืืขืจื ืึธื, ืืื ืืขืจ ืขืจืฉืืขืจ ืงืื ื ืคึผืจืึธืฆืขืก ืืื PID 9004, ืืึทืฉ ืกืืึทืจืฅ ื ืืฆื ืึท ืกืืกืืขื ืจืืคื ืื ืขืงืกืขืงืืืึทืืืข ืืขืงืข ืืืึธืก ืืืจ ืกืคึผืขืกืืคืืขื ืืืืฃ ืื ืืึทืคึฟืขืื ืฉืืจื, ืืื ืืื ืืืขืจ ืคืึทื ืขืก ืืื /usr/bin/cat.
ืืื ืื ืจืืข ืงืื ื ืคึผืจืึธืฆืขืก ืืื PID 9005, ืืึทืฉ ืืืืคื ืื ืจืืข ืขืงืกืขืงืืืึทืืืข ืืืจ ืกืคึผืขืกืืคืืขื, ืืื ืืื ืืืขืจ ืคืึทื /usr/bin/sleep.
ืื ืขืงืกืขืง ืกืืกืืขื ืจืืคื ืืื ื ืืฉื ืคืึทืจืืึทืื ืืขืงืข ืืึทื ืืึทืื ืกืืึทืื ืืื ืืขื ืขื ืืขืขืคื ื ืืื ืื O_CLOEXEC ืคืึธื ืืื ืืขืจ ืฆืืื ืืืขื ืื ืขืคืขื ืขื ืจืืคื ืืื ืืขืืืื. ืืื ืืื ืืืขืจ ืคืึทื, ื ืึธื ืืึธื ืืฉืื ื ืื ืขืงืกืขืงืืืึทืืืข ืืขืงืขืก, ืึทืืข ืงืจืึทื ื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืืืขื ืืืื ืืขืจืืืขืืืขื.
ืงืืง ืืื ืื ืงืึทื ืกืึธืื:
[user@localhost ]$ pgrep -P 15771
9004
9005
[user@localhost ]$ ls -lah /proc/15771/fd/
total 0
dr-x------ 2 user user 0 Oct 7 15:42 .
dr-xr-xr-x 9 user user 0 Oct 7 15:42 ..
lrwx------ 1 user user 64 Oct 7 15:42 0 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 2 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:42 255 -> /dev/pts/21
[user@localhost ]$ ls -lah /proc/9004/fd
total 0
dr-x------ 2 user user 0 Oct 7 15:57 .
dr-xr-xr-x 9 user user 0 Oct 7 15:57 ..
lrwx------ 1 user user 64 Oct 7 15:57 0 -> /dev/pts/21
l-wx------ 1 user user 64 Oct 7 15:57 1 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:57 2 -> /dev/pts/21
lr-x------ 1 user user 64 Oct 7 15:57 3 -> /dev/zero
[user@localhost ]$ ls -lah /proc/9005/fd
total 0
dr-x------ 2 user user 0 Oct 7 15:57 .
dr-xr-xr-x 9 user user 0 Oct 7 15:57 ..
lr-x------ 1 user user 64 Oct 7 15:57 0 -> pipe:[253543032]
lrwx------ 1 user user 64 Oct 7 15:57 1 -> /dev/pts/21
lrwx------ 1 user user 64 Oct 7 15:57 2 -> /dev/pts/21
[user@localhost ]$ ps -up 9004
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
user 9004 0.0 0.0 107972 620 pts/21 S+ 15:57 0:00 cat /dev/zero
[user@localhost ]$ ps -up 9005
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
user 9005 0.0 0.0 107952 360 pts/21 S+ 15:57 0:00 sleep 10000
ืืื ืืืจ ืงืขื ืขื ืืขื, ืื ืืื ืฆืืง ื ืืืขืจ ืคืื ืืื ืืืขืจ ืจืขืจ ืืื ืื ืืขืืืข ืืื ืืืืืข ืคึผืจืึทืกืขืกืึทื. ืืืื ืืืจ ืืึธืื ืึท ืงืฉืจ ืฆืืืืฉื ืฆืืืื ืคืึทืจืฉืืืขื ืข ืคึผืจืึทืกืขืกืึทื ืืื ืื ืืขืืืข ืคืึธืืขืจ.
ืคึฟืึทืจ ืื ืืืืก ืืขื ืขื ื ืืฉื ืืึทืงืึทื ื ืืื ืื ืกืืกืืขื ืจืืคื ืึทื bash ื ืืฆื, ืืื ืืขืืกื ืจืขืงืึธืืขื ืืืจื ืฆื ืืืืคื ืื ืงืึทืืึทื ืื ืืืจื ืกืืจืึทืกืข ืืื ืืขื ืืืึธืก ืืื ืืขืฉืขืขื ืืฉ ืื ืขืืืืื ืืง, ืคึฟืึทืจ ืืืึทืฉืคึผืื ืืื ืืึธืก:
strace -s 1024 -f bash -c "ls | grep hello"
ืืึธืืืจ ืฆืืจืืงืงืืืขื ืฆื ืืื ืืืขืจ ืคึผืจืึธืืืขื ืืื ื ืืืขืจืืง ืืืกืง ืคึผืืึทืฅ ืืื ืืจืืื ื ืฆื ืจืึทืืขืืืขื ืืึทืื ืึธื ืจืืกืืึทืจืืื ื ืืขื ืคึผืจืึธืฆืขืก. ืืื ืก ืฉืจืืึทืื ืึท ืงืืืื ืคึผืจืึธืืจืึทื ืืืึธืก ืืืขื ืฉืจืืึทืื ืืขืขืจืขื 1 ืืขืืืืืื ืคึผืขืจ ืกืขืงืื ืืข ืฆื ืืืกืง. ืืขืจืฆื, ืืืื ืคึฟืึทืจ ืขืืืขืืข ืกืืื ืืืจ ืืขื ืขื ื ืืฉื ืืืืืืช ืฆื ืฉืจืืึทืื ืืึทืื ืฆื ืื ืืืกืง, ืืืจ ืืืขืื ืคืฉืื ืืืื ืึธืจืืจื ืืขื ืืื ืคึผืจืืืืจื ืฆื ืฉืจืืึทืื ืื ืืึทืื ืืืืืขืจ ืืื ืึท ืจืืข. ืืื ืืขื ืืืึทืฉืคึผืื ืืื ื ืืฆื ืคึผืืืืึธื, ืืืจ ืงืขื ืขื ื ืืฆื ืงืืื ืื ืืขืจืข ืคึผืจืึธืืจืึทืืืื ื ืฉืคึผืจืึทื.
[user@localhost ]$ cat openforwrite.py
import datetime
import time
mystr="a"*1024*1024+"n"
with open("123.txt", "w") as f:
while True:
try:
f.write(str(datetime.datetime.now()))
f.write(mystr)
f.flush()
time.sleep(1)
except:
pass
ืืึธืืืจ ืืืืคื ืืขื ืคึผืจืึธืืจืึทื ืืื ืงืืง ืืื ืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก
[user@localhost ]$ python openforwrite.py &
[1] 3762
[user@localhost ]$ ps axuf | grep [o]penforwrite
user 3762 0.0 0.0 128600 5744 pts/22 S+ 16:28 0:00 | _ python openforwrite.py
[user@localhost ]$ ls -la /proc/3762/fd
total 0
dr-x------ 2 user user 0 Oct 7 16:29 .
dr-xr-xr-x 9 user user 0 Oct 7 16:29 ..
lrwx------ 1 user user 64 Oct 7 16:29 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 7 16:29 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 7 16:29 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 7 16:29 3 -> /home/user/123.txt
ืืื ืืืจ ืงืขื ืขื ืืขื, ืืืจ ืืึธืื ืืื ืืืขืจ 3 ื ืึธืจืืึทื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืืื ืืืื ืขืจ ืืขืจ ืืืึธืก ืืืจ ืืขืขืคื ื. ืืึธืืืจ ืงืึธื ืืจืึธืืืจื ืื ืืขืงืข ืืจืืืก:
[user@localhost ]$ ls -lah 123.txt
-rw-rw-r-- 1 user user 117M Oct 7 16:30 123.txt
ืื ืืึทืื ืืขื ืขื ืืขืฉืจืืื, ืืืจ ืคึผืจืืืืจื ืฆื ืืืืฉื ืื ืคึผืขืจืืืฉืึทื ื ืืืืฃ ืืขืจ ืืขืงืข:
[user@localhost ]$ sudo chown root: 123.txt
[user@localhost ]$ ls -lah 123.txt
-rw-rw-r-- 1 root root 168M Oct 7 16:31 123.txt
[user@localhost ]$ ls -lah 123.txt
-rw-rw-r-- 1 root root 172M Oct 7 16:31 123.txt
ืืืจ ืืขื ืึทื ืื ืืึทืื ืืขื ืขื ื ืึธื ืืขืฉืจืืื, ืืึธืืฉ ืืื ืืืขืจ ืืึทื ืืฆืขืจ ืืื ื ืืฉื ืืึธืื ืืขืจืืืืืขื ืืฉ ืฆื ืฉืจืืึทืื ืฆื ืืขืจ ืืขืงืข. ืืื ืก ืคึผืจืืืืจื ืฆื ืืึทืืืึทืืืงื ืขืก:
[user@localhost ]$ sudo rm 123.txt
[user@localhost ]$ ls 123.txt
ls: cannot access 123.txt: No such file or directory
ืืื ืืื ืื ืืึทืื ืืขืฉืจืืื? ืืื ืืื ืืขื ืขื ืืืื ืืขืฉืจืืื? ืืืจ ืงืึธื ืืจืึธืืืจื:
[user@localhost ]$ ls -la /proc/3762/fd
total 0
dr-x------ 2 user user 0 Oct 7 16:29 .
dr-xr-xr-x 9 user user 0 Oct 7 16:29 ..
lrwx------ 1 user user 64 Oct 7 16:29 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 7 16:29 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 7 16:29 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 7 16:29 3 -> /home/user/123.txt (deleted)
ืืึธ, ืืื ืืืขืจ ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ื ืึธื ืืืืืกืฅ ืืื ืืืจ ืงืขื ืขื ืืืึทืื ืืขื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ืืื ืืื ืืืขืจ ืึทืื ืืขืงืข, ืืืจ ืงืขื ืขื ืืืืขื ืขื, ืงืืึธืจ ืืื ื ืึธืืืึทืื ืขืก.
ืืื ืก ืงืืง ืืื ืื ืืขืงืข ืืจืืืก:
[user@localhost ]$ lsof | grep 123.txt
python 31083 user 3w REG 8,5 19923457 2621522 /home/user/123.txt
ืื ืืขืงืข ืืจืืืก ืืื 19923457. ืืึธืืืจ ืคึผืจืืืืจื ืฆื ืืืกืืขืงื ืื ืืขืงืข:
[user@localhost ]$ truncate -s 0 /proc/31083/fd/3
[user@localhost ]$ lsof | grep 123.txt
python 31083 user 3w REG 8,5 136318390 2621522 /home/user/123.txt
ืืื ืืืจ ืงืขื ืขื ืืขื, ืื ืืขืงืข ืืจืืืก ืืื ืืืืื ืื ืงืจืืกืื ื ืืื ืืื ืืืขืจ ืฉืืึทื ืืื ื ืืฉื ืึทืจืืขืื. ืืื ืก ืงืืง ืืื ืื ืกืืกืืขื ืจืืคื ืืึทืงืืืืขื ืืืืฉืึทื . ืืืื ืืืจ ื ืืฆื ืื O_APPEND ืคืึธื ืืืขื ืขืคื ืึท ืืขืงืข, ืืขืืึธืื ืืื ืืขืืขืจ ืฉืจืืึทืื, ืื ืึธืคึผืขืจืืืืื ื ืกืืกืืขื ืืฉืขืง ืื ืืขืงืข ืืจืืืก ืืื ืฉืจืืืื ืืึทืื ืฆื ืื ืกืืฃ ืคืื ืืขืจ ืืขืงืข, ืืื ืืื ืืึธืก ืึทืืึธืืืฉืข. ืืึธืก ืึทืืึทืื ืงืืืคื ืคึฟืขืืขื ืึธืืขืจ ืคึผืจืึทืกืขืกืึทื ืฆื ืฉืจืืึทืื ืฆื ืืขืจ ืืขืืืืงืขืจ ืืขืงืข. ืึธืืขืจ ืืื ืืื ืืืขืจ ืงืึธื ืืืจ ืืึธื ื ืื ื ืืฆื ืืขื ืคืึธื. ืืืจ ืงืขื ืขื ืืขื ืึท ืึทื ืืขืจืฉ ืืขืงืข ืืจืืืก ืืื lsof ื ืึธื ืืื ืืืืื ืืืื ืืืจ ืขืคืขื ืขื ืื ืืขืงืข ืคึฟืึทืจ ื ืึธื ืฉืจืืืื, ืืืึธืก ืืืื ืืื ืืื ืืืขืจ ืงืึธื ืึทื ืฉืืึธื
with open("123.txt", "w") as f:
ืืืจ ืืึธืื ืฆื ืฉืืขืื
with open("123.txt", "a") as f:
ืืฉืขืง ืืื ืื "ืื" ืคืึธื
[user@localhost ]$ strace -e trace=open python openforwrite.py 2>&1| grep 123.txt
open("123.txt", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
ืืื ืืื ืื "ืึท" ืคืึธื
[user@localhost ]$ strace -e trace=open python openforwrite.py 2>&1| grep 123.txt
open("123.txt", O_WRONLY|O_CREAT|O_APPEND, 0666) = 3
ืคึผืจืึธืืจืึทืืืื ื ืึท ืฉืืื ืคืืืกื ืืืง ืคึผืจืึธืฆืขืก
ืึธืคื ืคึผืจืึธืืืจืึทืืขืจื, ืืืขื ืงืจืืืืืื ื ืืื ืืขืกืืื ื ืืืืื, ื ืืฆื ืืืืืืขืจื (ืืืฉื GDB) ืึธืืขืจ ืคืึทืจืฉืืื ืืขืืืขืืก ืคืื ืืึธืืื ื ืืื ืื ืึทืคึผืืึทืงืืืฉืึทื. ืืื ืืงืก ืืื ืื ืคืืืืงืืื ืฆื ืึทืงืืฉืึทืืืึทืื ืฉืจืืึทืื ืืื ืืืืฉื ืึท ืฉืืื ืคืืืกื ืืืง ืคึผืจืึธืืจืึทื, ืืืฉื, ืืืืฉื ืื ืืืึทืืืขืก ืคืื ืืืขืจืืึทืืึทืื, ืฉืืขืื ืึท ืืจืืืงืคึผืืื ื, ืืื"ื ื.
ืฆืืจืืง ืฆื ืืขืจ ืึธืจืืืื ืขื ืงืฉืื ืืืขืื ื ืืฉื ืืขื ืื ืืืกืง ืคึผืืึทืฅ ืฆื ืฉืจืืึทืื ืึท ืืขืงืข, ืืึธืืืจ ืคึผืจืืืืจื ืฆื ืกืืืืืืจื ืืขื ืคึผืจืึธืืืขื.
ืืึธืืืจ ืืึทืื ืึท ืืขืงืข ืคึฟืึทืจ ืืื ืืืขืจ ืฆืขืืืืืื ื, ืืืึธืก ืืืจ ืืืขืื ืึธื ืงืืึทืคึผื ืืื ืึท ืืึทืืื ืืขืจ ืืืกืง:
[user@localhost ~]$ dd if=/dev/zero of=~/tempfile_for_article.dd bs=1M count=10
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 0.00525929 s, 2.0 GB/s
[user@localhost ~]$
ืืึธืืืจ ืฉืึทืคึฟื ืึท ืืขืงืข ืกืืกืืขื:
[user@localhost ~]$ mkfs.ext4 ~/tempfile_for_article.dd
mke2fs 1.42.9 (28-Dec-2013)
/home/user/tempfile_for_article.dd is not a block special device.
Proceed anyway? (y,n) y
...
Writing superblocks and filesystem accounting information: done
[user@localhost ~]$
ืื ืกืืึทืืืจื ืื ืืขืงืข ืกืืกืืขื:
[user@localhost ~]$ sudo mount ~/tempfile_for_article.dd /mnt/
[sudo] password for user:
[user@localhost ~]$ df -h | grep mnt
/dev/loop0 8.7M 172K 7.9M 3% /mnt
ืืืจ ืฉืึทืคึฟื ืึท ืืืขืืืืืึทืืขืจ ืืื ืืื ืืืขืจ ืืึทืืืฆืขืจ:
[user@localhost ~]$ sudo mkdir /mnt/logs
[user@localhost ~]$ sudo chown user: /mnt/logs
ืืึธืืืจ ืขืคึฟืขื ืขื ืื ืืขืงืข ืคึฟืึทืจ ืฉืจืืืื ืืืืื ืืื ืืื ืืืขืจ ืคึผืจืึธืืจืึทื:
with open("/mnt/logs/123.txt", "w") as f:
ืงืึทืืขืจ
[user@localhost ]$ python openforwrite.py
ืืืจ ืืืึทืจืื ืึท ืืืกื ืกืขืงืื ืืขืก
[user@localhost ~]$ df -h | grep mnt
/dev/loop0 8.7M 8.0M 0 100% /mnt
ืึทืืื, ืืืจ ืืึธืื ืื ืคึผืจืึธืืืขื ืืืกืงืจืืืื ืืื ืื ืึธื ืืืื ืคืื ืืขื ืึทืจืืืงื. ืคึฟืจืืึท ืคึผืืึทืฅ 0, 100% ืคืึทืจื ืืืขื.
ืืืจ ืืขืืขื ืงืขื ืึทื ืืืื ืื ืืืืื ืืื ืืขื ืคืื ืื ืึทืจืืขื, ืืืจ ืืขื ืขื ืืจืืื ื ืฆื ืจืขืงืึธืจืืืจื ืืืืขืจ ืืืืืืืง ืืึทืื ืืืึธืก ืงืขื ืขื ื ืื ืืืื ืคืึทืจืคืึทืื. ืืื ืืื ืืขืจ ืืขืืืืงืขืจ ืฆืืื, ืืืจ ืืึทืจืคึฟื ืฆื ืคืึทืจืจืืืื ืื ืืื ืกื ืึธื ืจืืกืืึทืจืืื ื ืืขื ืคึผืจืึธืฆืขืก.
ืืื ืก ืืึธืื ืืืจ ื ืึธื ืืึธืื ืืืกืง ืคึผืืึทืฅ, ืึธืืขืจ ืืื ืึท ืึทื ืืขืจืฉ ืฆืขืืืืืื ื, ืคึฟืึทืจ ืืืึทืฉืคึผืื ืืื / ืืืื.
ืืึธืืืจ ืคึผืจืืืืจื ืฆื "ืจืืคึผืจืึธืืืจืึทื ืืืืฃ ืื ืคืืืขื" ืืื ืืืขืจ ืงืึธื.
ืืึธืืืจ ืงืืง ืืื ืื PID ืคืื ืืื ืืืขืจ ืคึผืจืึธืฆืขืก, ืืืึธืก ืืื ืืขืืขืกื ืึทืืข ืื ืืืกืง ืคึผืืึทืฅ:
[user@localhost ~]$ ps axuf | grep [o]penfor
user 10078 27.2 0.0 128600 5744 pts/22 R+ 11:06 0:02 | _ python openforwrite.py
ืคืึทืจืืื ืื ืฆื ืืขื ืคึผืจืึธืฆืขืก ืืืจื gdb
[user@localhost ~]$ gdb -p 10078
...
(gdb)
ืืื ืก ืงืืง ืืื ืื ืขืคืขื ืขื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก:
(gdb) shell ls -lah /proc/10078/fd/
total 0
dr-x------ 2 user user 0 Oct 8 11:06 .
dr-xr-xr-x 9 user user 0 Oct 8 11:06 ..
lrwx------ 1 user user 64 Oct 8 11:09 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:09 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:06 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:09 3 -> /mnt/logs/123.txt
ืืืจ ืงืืงื ืืื ืื ืืื ืคึฟืึธืจืืึทืฆืืข ืืืขืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ื ืืืขืจ 3, ืืืึธืก ืืื ืืขืจืขืก ืืื ืื
(gdb) shell cat /proc/10078/fdinfo/3
pos: 8189952
flags: 0100001
mnt_id: 482
ืืืืื ืืื ืืื ืขื ืืืึธืก ืกืืกืืขื ืจืืคื ืคึผืืืืึธื ืืืื (ืืขื ืืืืื ืืื ืืืจ ืืขืืืคื ืกืืจืึทืกืข ืืื ืืขืคึฟืื ืขื ืืขื ืขืคืขื ืขื ืจืืคื), ืืืขื ืคึผืจืึทืกืขืกืื ื ืืื ืืืขืจ ืงืึธื ืฆื ืขืคืขื ืขื ืึท ืืขืงืข, ืืืจ ืืึธื ืื ืืขืืืข ืืื ืืืืฃ ืืืืึทืฃ ืคืื ืืื ืืืขืจ ืคึผืจืึธืฆืขืก, ืึธืืขืจ ืืืจ ืืึทืจืคึฟื ืื O_WRONLY|O_CREAT| O_TRUNC ืืืื ืคืึทืจืืืึทืื ืืื ืึท ื ืืืขืจืืง ืืืขืจื. ืฆื ืืึธื ืืึธืก, ืืืฉื, ืขืคึฟืขื ืขื ืื ืงืขืจื ืงืืืืื ืืื ืงืืง ืืื ืืืึธืก ืคืืึทืืก ืืขื ืขื ืคืึทืจืึทื ืืืืึธืจืืืขื ืคึฟืึทืจ ืืืึธืก
# ืืขืคืื ืืจื O_WRONLY 00000001
# ืืขืคืื ืืจื O_CREAT 00000100
# ืืขืคืื ืืจื O_TRUNC 00001000
ืืืจ ืคืึทืจืืื ืื ืึทืืข ืื ืืืึทืืืขืก ืืื ืืืื, ืืืจ ืืึทืงืืืขื 00001101
ืืืจ ืืืืคื ืืื ืืืขืจ ืจืืคื ืคืื ืืื
(gdb) call open("/home/user/123.txt", 00001101,0666)
$1 = 4
ืึทืืื ืืืจ ืืึธืื ืึท ื ืืึทืข ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ืืื ื ืืืขืจ 4 ืืื ืึท ื ืืึทืข ืึธืคึฟื ืืขืงืข ืืืืฃ ืื ืื ืืขืจ ืฆืขืืืืืื ื, ืืืจ ืงืึธื ืืจืึธืืืจื:
(gdb) shell ls -lah /proc/10078/fd/
total 0
dr-x------ 2 user user 0 Oct 8 11:06 .
dr-xr-xr-x 9 user user 0 Oct 8 11:06 ..
lrwx------ 1 user user 64 Oct 8 11:09 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:09 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:06 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:09 3 -> /mnt/logs/123.txt
l-wx------ 1 user user 64 Oct 8 11:15 4 -> /home/user/123.txt
ืืืจ ืืขืืขื ืงืขื ืืขื ืืืืฉืคึผืื ืืื ืจืขืจ - ืืื ืืึทืฉ ืขื ืืขืจืื ืืขื ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก, ืืื ืืืจ ืืึธืื ืฉืืื ืืขืืขืจื ื ืื ืืืคึผ2 ืกืืกืืขื ืจืืคื.
ืืืจ ืคึผืจืืืืจื ืฆื ืคืึทืจืืืึทืื ืืืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ ืืื ืื ืืขืจื
(gdb) call dup2(4,3)
$2 = 3
ืืืจ ืงืึธื ืืจืึธืืืจื:
(gdb) shell ls -lah /proc/10078/fd/
total 0
dr-x------ 2 user user 0 Oct 8 11:06 .
dr-xr-xr-x 9 user user 0 Oct 8 11:06 ..
lrwx------ 1 user user 64 Oct 8 11:09 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:09 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:06 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:09 3 -> /home/user/123.txt
l-wx------ 1 user user 64 Oct 8 11:15 4 -> /home/user/123.txt
ืืืจ ืคืึทืจืืึทืื ืืขืงืข ืืืกืงืจืืคึผืืึธืจ 4, ืืืืึทื ืืืจ ืืึธื ื ืื ืืึทืจืคึฟื ืขืก:
(gdb) call close (4)
$1 = 0
ืืื ืึทืจืืืกืืืื ืืื
(gdb) quit
A debugging session is active.
Inferior 1 [process 10078] will be detached.
Quit anyway? (y or n) y
Detaching from program: /usr/bin/python2.7, process 10078
ืืฉืขืง ืื ื ืืึทืข ืืขืงืข:
[user@localhost ~]$ ls -lah /home/user/123.txt
-rw-rw-r-- 1 user user 5.1M Oct 8 11:18 /home/user/123.txt
[user@localhost ~]$ ls -lah /home/user/123.txt
-rw-rw-r-- 1 user user 7.1M Oct 8 11:18 /home/user/123.txt
ืืื ืืืจ ืงืขื ืขื ืืขื, ืื ืืึทืื ืืขื ืขื ืืขืฉืจืืื ืฆื ืึท ื ืืึทืข ืืขืงืข, ืืึธืืืจ ืงืึธื ืืจืึธืืืจื ืื ืึทืื:
[user@localhost ~]$ ls -lah /mnt/logs/123.txt
-rw-rw-r-- 1 user user 7.9M Oct 8 11:08 /mnt/logs/123.txt
ืงืืื ืืึทืื ืืขื ืขื ืคืึทืจืคืึทืื, ืื ืึทืคึผืืึทืงืืืฉืึทื ืึทืจืืขื, ืืึธืืก ืืขื ืขื ืืขืฉืจืืื ืฆื ืึท ื ืืึทืข ืึธืจื.
ืืื ืก ืงืึธืืคึผืืืฆืืจื ืื ืึทืจืืขื ืึท ืืืกื
ืืื ืก ืืืึทืืืฉืึทื ืึทื ืื ืืึทืื ืืขื ืขื ืืืืืืืง ืคึฟืึทืจ ืืื ืื, ืึธืืขืจ ืืืจ ืืึธื ื ืื ืืึธืื ืืืกืง ืคึผืืึทืฅ ืืื ืงืืื ืคืื ืื ืคึผืึทืจืืืฉืึทื ื ืืื ืืืจ ืงืขื ืขื ื ืืฉื ืคืึทืจืืื ืื ืื ืืืกืง.
ืืืึธืก ืืืจ ืงืขื ืขื ืืึธื ืืื ืจืืืขืจืขืงื ืืื ืืืขืจ ืืึทืื ืขืจืืขืฅ, ืคึฟืึทืจ ืืืึทืฉืคึผืื ืฆื ืจืขืจ, ืืื ืืื ืงืขืจ ืจืืืขืจืขืงื ืืึทืื ืคืื ืจืขืจ ืฆื ืื ื ืขืฅ ืืืจื ืขืืืขืืข ืคึผืจืึธืืจืึทื, ืืืฉื ื ืขืืงืึทื.
ืืืจ ืงืขื ืขื ืืึทืื ืึท ืืขืืืืกื ืจืขืจ ืืื ืื mkfifo ืืึทืคึฟืขื. ืขืก ืืืขื ืืึทืื ืึท ืคึผืกืขืืืืึธ ืืขืงืข ืืืืฃ ืืขืจ ืืขืงืข ืกืืกืืขื ืืคืืื ืืืื ืขืก ืืื ืงืืื ืคืจืื ืคึผืืึทืฅ ืืืืฃ ืขืก.
ืจืืกืืึทืจื ืื ืึทืคึผืืึทืงืืืฉืึทื ืืื ืืฉืขืง:
[user@localhost ]$ python openforwrite.py
[user@localhost ~]$ ps axuf | grep [o]pen
user 5946 72.9 0.0 128600 5744 pts/22 R+ 11:27 0:20 | _ python openforwrite.py
[user@localhost ~]$ ls -lah /proc/5946/fd
total 0
dr-x------ 2 user user 0 Oct 8 11:27 .
dr-xr-xr-x 9 user user 0 Oct 8 11:27 ..
lrwx------ 1 user user 64 Oct 8 11:28 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:28 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:27 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:28 3 -> /mnt/logs/123.txt
[user@localhost ~]$ df -h | grep mnt
/dev/loop0 8.7M 8.0M 0 100% /mnt
ืขืก ืืื ืงืืื ืืืกืง ืคึผืืึทืฅ, ืึธืืขืจ ืืืจ ืืฆืืื ืฉืึทืคึฟื ืึท ืืขืืืืกื ืจืขืจ ืืึธืจื:
[user@localhost ~]$ mkfifo /mnt/logs/megapipe
[user@localhost ~]$ ls -lah /mnt/logs/megapipe
prw-rw-r-- 1 user user 0 Oct 8 11:28 /mnt/logs/megapipe
ืืืฆื ืืืจ ืืึทืจืคึฟื ืฆื ืขืคืขืก ืืึทื ืืืืงืืขื ืึทืืข ืื ืืึทืื ืืืึธืก ืืืื ืืื ืืขื ืจืขืจ ืฆื ืื ืื ืืขืจ ืกืขืจืืืขืจ ืืืจื ืื ื ืขืฅ; ืืขืจ ืืขืืืืงืขืจ ื ืขืืงืึทื ืืื ืคึผืึทืกืืง ืคึฟืึทืจ ืืขื.
ืืืืฃ ืื ืกืขืจืืืขืจ ืืืืึทื-server.example.com ืืืจ ืืืืคื
[user@localhost ~]$ nc -l 7777 > 123.txt
ืืืืฃ ืืื ืืืขืจ ืคึผืจืึธืืืขืืึทืืืง ืกืขืจืืืขืจ ืืืจ ืงืึทืืขืจ ืืื ืึท ืืึทืืื ืืขืจ ืืืึธืงืืึทื
[user@localhost ~]$ nc remote-server.example.com 7777 < /mnt/logs/megapipe
ืืืฆื ืึทืืข ืื ืืึทืื ืืืึธืก ืขื ืืก ืืื ืื ืจืขืจ ืืืขื ืืืืืึธืืึทืืืฉ ืืืื ืฆื ืกืืืื ืืื ื ืขืืงืึทื, ืืืึธืก ืืืขื ืฉืืงื ืขืก ืฆื ืื ื ืขืฅ ืืืืฃ ืคึผืึธืจื 7777.
ืื ืืืจ ืืึธืื ืฆื ืืึธื ืืื ืึธื ืืืืื ืฆื ืฉืจืืึทืื ืืื ืืืขืจ ืืึทืื ืืื ืืขื ืืขืืืืกื ืจืขืจ.
ืืืจ ืืึธืื ืฉืืื ืื ืึทืคึผืืึทืงืืืฉืึทื ืคืืืกื ืืืง:
[user@localhost ~]$ ps axuf | grep [o]pen
user 5946 99.8 0.0 128600 5744 pts/22 R+ 11:27 169:27 | _ python openforwrite.py
[user@localhost ~]$ ls -lah /proc/5946/fd
total 0
dr-x------ 2 user user 0 Oct 8 11:27 .
dr-xr-xr-x 9 user user 0 Oct 8 11:27 ..
lrwx------ 1 user user 64 Oct 8 11:28 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:28 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:27 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:28 3 -> /mnt/logs/123.txt
ืคืื ืึทืืข ืคืืึทืืก, ืืืจ ื ืึธืจ ืืึทืจืคึฟื O_WRONLY ืืื ื ืื ืืขืงืข ืืื ืฉืืื ืืืืืกืฅ ืืื ืืืจ ืืึธื ื ืื ืืึทืจืคึฟื ืฆื ืืืกืืขืงื ืขืก
[user@localhost ~]$ gdb -p 5946
...
(gdb) call open("/mnt/logs/megapipe", 00000001,0666)
$1 = 4
(gdb) shell ls -lah /proc/5946/fd
total 0
dr-x------ 2 user user 0 Oct 8 11:27 .
dr-xr-xr-x 9 user user 0 Oct 8 11:27 ..
lrwx------ 1 user user 64 Oct 8 11:28 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:28 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:27 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:28 3 -> /mnt/logs/123.txt
l-wx------ 1 user user 64 Oct 8 14:20 4 -> /mnt/logs/megapipe
(gdb) call dup2(4,3)
$2 = 3
(gdb) shell ls -lah /proc/5946/fd
total 0
dr-x------ 2 user user 0 Oct 8 11:27 .
dr-xr-xr-x 9 user user 0 Oct 8 11:27 ..
lrwx------ 1 user user 64 Oct 8 11:28 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:28 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:27 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:28 3 -> /mnt/logs/megapipe
l-wx------ 1 user user 64 Oct 8 14:20 4 -> /mnt/logs/megapipe
(gdb) call close(4)
$3 = 0
(gdb) shell ls -lah /proc/5946/fd
total 0
dr-x------ 2 user user 0 Oct 8 11:27 .
dr-xr-xr-x 9 user user 0 Oct 8 11:27 ..
lrwx------ 1 user user 64 Oct 8 11:28 0 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:28 1 -> /dev/pts/22
lrwx------ 1 user user 64 Oct 8 11:27 2 -> /dev/pts/22
l-wx------ 1 user user 64 Oct 8 11:28 3 -> /mnt/logs/megapipe
(gdb) quit
A debugging session is active.
Inferior 1 [process 5946] will be detached.
Quit anyway? (y or n) y
Detaching from program: /usr/bin/python2.7, process 5946
ืงืึธื ืืจืึธืืืจืื ื ืื ืืืืึทื ืกืขืจืืืขืจ remote-server.example.com
[user@localhost ~]$ ls -lah 123.txt
-rw-rw-r-- 1 user user 38M Oct 8 14:21 123.txt
ืื ืืึทืื ืงืืืขื, ืืืจ ืงืึธื ืืจืึธืืืจื ืื ืคึผืจืึธืืืขื ืกืขืจืืืขืจ
[user@localhost ~]$ ls -lah /mnt/logs/
total 7.9M
drwxr-xr-x 2 user user 1.0K Oct 8 11:28 .
drwxr-xr-x 4 root root 1.0K Oct 8 10:55 ..
-rw-rw-r-- 1 user user 7.9M Oct 8 14:17 123.txt
prw-rw-r-- 1 user user 0 Oct 8 14:22 megapipe
ืื ืืึทืื ืืื ืืขืจืืืขืืืขื, ืื ืคึผืจืึธืืืขื ืืื ืกืึทืืืื.
ืืื ื ืืฆื ืื ืืขืืขืื ืืืื ืฆื ืืึธืื ืืขืื ืฆื ืืืื ืืืจืื ืคืื ืืขืืืจืึธ.
ืืขืจื ืฆื Radio T ืคึผืึธืืงืึทืกืฅ.
ืืื ืฆื ืึทืืข.
ืืื ืืขืงืฆืืขืก, ืืื ืคึฟืึธืจืฉืืึธืื ืืืจ ืืจืึทืืื ืืืขืื ืืืึธืก ืืืขื ืืืื ืืื ืืขื ืคึผืจืึธืฆืขืก ืืขืงืข ืืืกืงืจืืคึผืืึธืจืก ืงืึทืฅ ืืื ืฉืืึธืคื ืืืื ืืืจ ืืืืคื ืื ืคืืืืขื ืืข ืืึทืคึฟืขื:
[user@localhost ~]$ cat /dev/zero 2>/dev/null| sleep 10000
ืืงืืจ: www.habr.com