Re: grep・sedの正規表現について

[root@host etc]# pwd
/etc

[root@host etc]# grep -E 'igm?p' protocols
igmp    2       IGMP            # internet group management protocol
igp     9       IGP             # any private interior gateway (Cisco: for IGRP)
nsfnet-igp      85      NSFNET-IGP      # NSFNET-IGP

[root@host etc]# grep -E 'c+p' protocols
tcp     6       TCP             # transmission control protocol
dccp    33      DCCP            # Datagram Congestion Control Protocol
cpnx    72      CPNX            # Computer Protocol Network Executive
cphb    73      CPHB            # Computer Protocol Heart Beat
micp    95      MICP            # Mobile Internetworking Control Pro.
scps    105     SCPS            # SCPS

[root@host etc]# grep -E '+tp' protocols
# See also http://www.iana.org/assignments/protocol-numbers
irtp    28      IRTP            # Internet Reliable Transaction Protocol
iso-tp4 29      ISO-TP4         # ISO Transport Protocol Class 4
xtp     36      XTP             # Xpress Tranfer Protocol
idpr-cmtp       38      IDPR-CMTP       # IDPR Control Message Transport Proto
tp++    39      TP++            # TP++ Transport Protocol
cftp    62      CFTP            # CFTP
vmtp    81      VMTP            # Versatile Message Transport
secure-vmtp     82      SECURE-VMTP     # SECURE-VMTP
ttp     84      TTP             # TTP
mtp     92      MTP             # Multicast Transport Protocol
gmtp    100     GMTP            # GMTP
l2tp    115     L2TP            # Layer Two Tunneling Protocol
iatp    117     IATP            # Interactive Agent Transfer Protocol
stp     118     STP             # Schedule Transfer
ptp     123     PTP             # Performance Transparency Protocol
crtp    126     CRTP            # Combat Radio Transport Protocol
sctp    132     SCTP            # Stream Control Transmission Protocol