将命令输出附加到文件的每一行

Question

I have a script test.sh

#!/bin/bash
route add -net <IP1> netmask 0.0.0.0 gw 10.xx.xx.1 dev eth0
route add -net <IP2> netmask 0.0.0.0 gw 10.xx.xx.1 dev eth0

I have created a function get_alias in another script which gets alias value corresponds to ip address.

I want to append the get_alias command output of corresponding ip to each line (except top most) of test.sh

So suppose if

$(get_alias IP1) is 1 and $(get_alias IP2) is 2

So my desired file should be as below:

#!/bin/bash
route add -net <IP1> netmask 0.0.0.0 gw 10.xx.xx.1 dev eth0:1
route add -net <IP2> netmask 0.0.0.0 gw 10.xx.xx.1 dev eth0:2

I have tried below awk but this is not working

awk  '{ print $0":"$(get_alias "$4") }' test.sh 

Answer 1

Instead of awk i have used while to resolve the issue:

while read -r line ; do
    ip=$(echo $line | cut -d " " -f 4)
    alias="$(get_alias "$ip")"
    echo "$line:$alias"
done < test.sh > test_out.sh

Answer 2

A slow bash while loop:

(
    # ignore first line
    IFS= read -r line; 
    printf "%s\n" "$line";
    # for the rest of the lines
    while IFS= read -r line; do
         # get the ip address
         IFS=$' \t' read _ _ _ ip _ <<<"$line"
         # output the line with `:` with the output of get_alias:
         printf "%s:%s\n" "$line" "$(get_alias "$ip")"
    done
) < test.sh

The script quite literally: - reads the first line and outputs it without a change - then while it reads the lines from file - we get the ip address as the 4 field from the line ( awk '{print $4}' and similar would work too) - then we print the line with the output of the get_alias function.