cat显示行号

cat -n

使用cat看长文件，尤其是配置文件，没有行号很不方便。

使用cat命令时，添加参数-n，可以在查看时显示行号。

e.g.
查看日志的配置文件

[root@C8-3 ~]# cat -n /etc/rsyslog.conf 
     1	# rsyslog configuration file
     2	
     3	# For more information see /usr/share/doc/rsyslog-*/rsyslog_conf.html
     4	# or latest version online at http://www.rsyslog.com/doc/rsyslog_conf.html 
     5	# If you experience problems, see http://www.rsyslog.com/doc/troubleshoot.html
     6	
     7	#### MODULES ####
     8	
     9	module(load="imuxsock" 	  # provides support for local system logging (e.g. via logger command)
    10	       SysSock.Use="off") # Turn off message reception via local log socket; 
    11				  # local messages are retrieved through imjournal now.
    12	module(load="imjournal" 	    # provides access to the systemd journal
    13	       StateFile="imjournal.state") # File to store the position in the journal
    14	#module(load="imklog") # reads kernel messages (the same are read from journald)
    15	#module(load"immark") # provides --MARK-- message capability
    16	
    17	# Provides UDP syslog reception
    18	# for parameters see http://www.rsyslog.com/doc/imudp.html
    19	#module(load="imudp") # needs to be done just once
    20	#input(type="imudp" port="514")
    21	
    22	# Provides TCP syslog reception
    23	# for parameters see http://www.rsyslog.com/doc/imtcp.html
    24	#module(load="imtcp") # needs to be done just once
    25	#input(type="imtcp" port="514")
    26	
    27	#### GLOBAL DIRECTIVES ####
    28	
    29	# Where to place auxiliary files
    30	global(workDirectory="/var/lib/rsyslog")
    31	
    32	# Use default timestamp format
    33	module(load="builtin:omfile" Template="RSYSLOG_TraditionalFileFormat")
    34	
    35	# Include all config files in /etc/rsyslog.d/
    36	include(file="/etc/rsyslog.d/*.conf" mode="optional")
    37	
    38	#### RULES ####
    39	
    40	# Log all kernel messages to the console.
    41	# Logging much else clutters up the screen.
    42	#kern.*                                                 /dev/console
    43	
    44	# Log anything (except mail) of level info or higher.
    45	# Don't log private authentication messages!
    46	*.info;mail.none;authpriv.none;cron.none                /var/log/messages
    47	
    48	# The authpriv file has restricted access.
    49	authpriv.*                                              /var/log/secure
    50	
    51	# Log all the mail messages in one place.
    52	mail.*                                                  -/var/log/maillog
    53	
    54	
    55	# Log cron stuff
    56	cron.*                                                  /var/log/cron
    57	
    58	# Everybody gets emergency messages
    59	*.emerg                                                 :omusrmsg:*
    60	
    61	# Save news errors of level crit and higher in a special file.
    62	uucp,news.crit                                          /var/log/spooler
    63	
    64	# Save boot messages also to boot.log
    65	local7.*                                                /var/log/boot.log
    66	
    67	
    68	# ### sample forwarding rule ###
    69	#action(type="omfwd"  
    70	# An on-disk queue is created for this action. If the remote host is
    71	# down, messages are spooled to disk and sent when it is up again.
    72	#queue.filename="fwdRule1"       # unique name prefix for spool files
    73	#queue.maxdiskspace="1g"         # 1gb space limit (use as much as possible)
    74	#queue.saveonshutdown="on"       # save messages to disk on shutdown
    75	#queue.type="LinkedList"         # run asynchronously
    76	#action.resumeRetryCount="-1"    # infinite retries if host is down
    77	# Remote Logging (we use TCP for reliable delivery)
    78	# remote_host is: name/ip, e.g. 192.168.0.1, port optional e.g. 10514
    79	#Target="remote_host" Port="XXX" Protocol="tcp")