Linux

concatenate a file list into a string

scripting




Example 1

kreese@myvps:arp $ 
205.178.186.72  
205.178.136.60  
205.178.136.72  
205.178.136.91  
205.178.136.109  
205.178.136.132  
205.178.136.166  
205.178.186.206  
205.178.186.220  
206.188.212.32  
206.188.212.142  
206.188.212.148  
206.188.212.163  
206.188.212.164  
206.188.212.165  
206.188.212.166  
206.188.212.167  
206.188.212.168  
206.188.212.169  
206.188.212.170  
206.188.212.171  
206.188.212.193  
69.161.223.12  
69.161.223.104  
69.161.223.236  
69.161.223.237  
206.188.208.186  
206.188.207.1  
206.188.207.209  
206.188.207.254  
206.188.206.50  
206.188.206.60  
206.188.206.178  
206.188.206.180  
206.188.204.129  
206.188.204.254  
kreese@myvps:arp $  
kreese@myvps:arp $ ips=$(< ./ips awk '$1')
kreese@myvps:arp $ echo $ips
205.178.186.72 205.178.136.60 205.178.136.72 205.178.136.91 205.178.136.109 205.178.136.132 205.178.136.166 205.178.186.206 205.178.186.220 206.188.212.32 206.188.212.142 206.188.212.148 206.188.212.163 206.188.212.164 206.188.212.165 206.188.212.166 206.188.212.167 206.188.212.168 206.188.212.169 206.188.212.170 206.188.212.171 206.188.212.193 69.161.223.12 69.161.223.104 69.161.223.236 69.161.223.237 206.188.208.186 206.188.207.1 206.188.207.209 206.188.207.254 206.188.206.50 206.188.206.60 206.188.206.178 206.188.206.180 206.188.204.129 206.188.204.254

Example 2:

nodevs=$(< /proc/filesystems awk ‘$1 == “nodev” { print $2 }’)

Example 3:

One of my favorites is when I need to kill off a bunch of processes belonging to a specific user. In comes in really handy when a customers VPS is hacked and they’ve created a privlidged user account where you want to quickly kill of a bunch of pids belonging to that user:

kill -9 $(ps -U 10000 | awk '{ print $1 }' | grep -v PID)

or use

ps -U apache -o pid --no-headers

Example 4:

Using tr

tr -s '\n' ' ' < file.txt

Example 5:

[root@vps11 ~]# for veid in $(cat vps5.migrations  | awk '{ print $4 }'); do echo -ne "$veid,"; done  
7879,7868,11370,7843,8493,12116,13739,7915,7954,8640,[root@vps11 ~]#
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