$grep -V GNU grep 2.6.3 Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. $ GREP -F or fgrep $grep -F H hello.txt Hello $grep -F helloKello …
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grep -n ,-v , -c, -i
$grep -n root /etc/passwd 1:root:x:0:0:root:/root:/bin/bash $ $cat hello.txt hello world $grep -v hello hello.txt world $ $cat hello.txt hello world helloo $grep -c hello hello.txt 2 $grep -c helloo hello.txt 1 $ $cat hello.txt hello world helloo Hello $grep hello hello.txt hello helloo $grep -i hello hello.txt hello helloo Hello $
grep ? (regex)
from grep info. GNU FDL `?’ The preceding item is optional and will be matched at most once. $cat bu.txt bugy buggy bugggy $ $grep -E bug\?y bu.txt bugy $grep -E bugg\?y bu.txt bugy buggy $grep -E buggg\?y bu.txt buggy bugggy $
grep * wildcard
to match repetitions of a character a star is used. $cat samsung id proof license copy check leaf 1 $grep *p* samsung $grep p* samsung id proof license copy check leaf 1 $grep p samsung id proof license copy $grep *p samsung $grep * samsung Binary file PCBSD8.0-x86-bootonly.iso matches $grep “*” samsung $grep “p*” samsung …
grep . wildcard
$cat samsung id proof license copy check leaf 1 $grep c.e samsung check leaf 1 $grep c.h samsung $
terminfo is a database of terminal capabilities
$cd /lib/terminfo/ $ls a c d E h l m p r s v w x $pwd /lib/terminfo $cd l/ $infocmp linux $infocmp linux # Reconstructed via infocmp from file: /lib/terminfo/l/linux linux|linux console, am, bce, ccc, eo, mir, msgr, xenl, xon, colors#8, it#8, ncv#18, pairs#64, Terminfo (formerly Termcap) is a database of terminal capabilities and …
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duplicate selective acknowledgement
$cat /proc/sys/net/ipv4/tcp_dsack 1 $ tcp_dsack – BOOLEAN Allows TCP to send “duplicate” SACKs. This option is required to send duplicate SACKs which was briefly described in the tcp_sack variable explanation. This is described in detail within the RFC 2883. This RFC document explains in detail how to handle situations where a packet is received twice …
knowledge discovery
Knowledge discovery is a concept of the field of computer science that describes the process of automatically searching large volumes of data for patterns that can be considered knowledge about the data. From Wikipedia, the free encyclopedia.
size of socket reads that will be offloaded to a DMA copy engine
$cat /proc/sys/net/ipv4/tcp_dma_copybreak 4096 $ tcp_dma_copybreak – INTEGER Lower limit, in bytes, of the size of socket reads that will be offloaded to a DMA copy engine, if one is present in the system and CONFIG_NET_DMA is enabled. Default: 4096 grepping through linux kernel source 2.6.32 sysctl_net_ipv4.c: .procname = “tcp_dma_copybreak”,
congestion control algorithm to be used for new connections
ahiliation:~$cat /proc/sys/net/ipv4/tcp_congestion_control cubic ahiliation:~$echo reno > /proc/sys/net/ipv4/tcp_congestion_control bash: /proc/sys/net/ipv4/tcp_congestion_control: Permission denied ahiliation:~$su – Password: debianlabs:~# echo reno > /proc/sys/net/ipv4/tcp_congestion_control debianlabs:~# cat /proc/sys/net/ipv4/tcp_congestion_control reno debianlabs:~# echo dreno > /proc/sys/net/ipv4/tcp_congestion_control -su: echo: write error: No such file or directory Set the congestion control algorithm to be used for new connections. The algorithm “reno” is always available, but …
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