将字符串附加到以某些字符开头的每个匹配模式

我将您的示例放置在名为input.txt的文件中

$ cat input.txt 
define command {
        command_name    check_nrpe_aix_load
        command_line    $USER1$/check_nrpe -p $USER11$ -H $HOSTADDRESS$ -a $ARG1$              $ARG2$ ARG3$
        }

define command {
        command_name   check_nrpe_aix_cpu_stats
        command_line    $USER1$/check_nrpe -p $USER11$ -H $HOSTADDRESS$ -a $ARG1$ $ARG2$
        }
现在，如果您运行：

awk 'BEGIN {OFS=""} {if ($0 ~ /check_nrpe_aix/) print $0,"_SOMESTRING";else print $0}' input.txt
您应该得到预期的结果：

$ awk 'BEGIN {OFS=""} {if ($0 ~ /check_nrpe_aix/) print $0,"_SOMESTRING";else print $0}' input.txt
define command {
        command_name    check_nrpe_aix_load_SOMESTRING
        command_line    $USER1$/check_nrpe -p $USER11$ -H $HOSTADDRESS$ -a $ARG1$ $ARG2$ ARG3$
        }

define command {
        command_name   check_nrpe_aix_cpu_stats_SOMESTRING
        command_line    $USER1$/check_nrpe -p $USER11$ -H $HOSTADDRESS$ -a $ARG1$ $ARG2$
        }