sed special caracters [bash script] issue

[tangi]

hi there,

I'm having issue when trying to change a line in a file

ip addr show "$1" | awk "/^.*inet.*$1$/{print $2}" | sed -n '1 s,/.*,,p'

to

ip -4 -o addr show primary dev $1 | awk '$3 == "inet" {print $4; exit}' | sed 's#/.*##'

this is what I've done

 sed -i "s/ip addr show \"$1\" | awk \"/^.*inet.*$1\$/{print \$2}\" | sed -n \'1 s,/.*,,p\'\/ip -4 -o addr show primary dev $1 | awk \'$3 \=\= "inet" {print $4; exit}\' | sed \'s#\/.*##\'/g" /etc/xen/scripts/vif-common.sh

sed- i "s/find/change/g" /etc/xen/scripts/vif-common.sh

can someone help me??

thanks

[drl]

Hi.

You seem to be wanting to replace a line in a shell script.

I find that situations like this cause me to make mistakes in quoting. The shell tries to interpret too much of the replacement line, so I use an additional file, "hiding" as much as possible so that the shell will not "see" the line. That avoids the task of trying out-think the shell for quoting.

With the replacement line in the additional file, you skip to the place where you want to replace the line, read the new line in, and print it. That effectively discards the old line. For any other line, you simply print the line, like this:

#!/usr/bin/env bash

# @(#) s1	Demonstrate how to avoid complex quoting.

# Utility functions: print-as-echo, print-line-with-visual-space.
pe() { for i;do printf "%s" "$i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }

pl " Input file data1:"
cat data1

pl " Replacement file data2:"
cat data2

pl " Results from awk:"
awk '
/ip addr show/	{ getline replacement < "data2" ; print replacement ; next }
	{ print }
' data1

exit 0

producing:

% ./s1

-----
 Input file data1:
one
two
ip addr show "$1" | awk "/^.*inet.*$1$/{print $2}" | sed -n '1 s,/.*,,p'
four
five

-----
 Replacement file data2:
ip -4 -o addr show primary dev $1 | awk '$3 == "inet" {print $4; exit}' | sed 's#/.*##'

-----
 Results from awk:
one
two
ip -4 -o addr show primary dev $1 | awk '$3 == "inet" {print $4; exit}' | sed 's#/.*##'
four
five

Best wishes ... cheers, drl