bash: smarter way for a setup script

Question

have anybody a smarter way to prepare template files via bash script?

This is the current script:

#!/bin/bash
projectDir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
echo "Project root: $projectDir"
echo "> Is this the project root directory? (y/n)"
read validProjectPath
#if [ "$isProjectDir" != "y" ] then exit 1 fi
echo "> Your OS user name (e.g. peter):"
read userName
echo "> VM IPv4 address (e.g. 192.168.178.2):"
read ipv4

# setup
echo "prepare configuration files..."
for f in $(find "$projectDir/vagrant" -name "*.template" -type f); do 
    toFile=${f/.template/}
    cp $f $f.bak
    sed "s/_CHANGE_PRODIR_/$projectDir/g" $f.bak > $f.bak1
    sed "s/_CHANGE_USERNAME_/$userName/g" $f.bak1 > $f.bak2
    sed "s/_CHANGE_IPV4_/$ipv4/g" $f.bak2 > $toFile
    rm -f $f.bak
    rm -f $f.bak1
    rm -f $f.bak2
done
echo "... done!"

Thanks for reply. Jim

oh yeah, the template files are redundant (sed -i -e). I've currently the error "prepare configuration files... sed: 1: "s/_CHANGE_PRODIR_//User ...": bad flag in substitute command: 'U' sed: 1: "s/_CHANGE_PRODIR_//User ...": bad flag in substitute command: 'U' ... done!" What's wrong and why is it printed two times (foreach case)? — Jim
– Jim, Commented Sep 1, 2014 at 6:38

tripleee · Accepted Answer · 2014-09-01 08:19:52Z

This whole temporary file business is entirely unnecessary.

for f in $(find "$projectDir/vagrant" -name "*.template" -type f); do
    sed -e "s%_CHANGE_PRODIR_%$projectDir%g" \
        -e "s%_CHANGE_USERNAME_%$userName%g" \
        -e "s%_CHANGE_IPV4_%$ipv4%g" "$f"> "${f/.template/}"
done

If your sed dialect doesn't like multiple -e options, try putting the entire script between double quotes with newlines or semicolons between the commands.

    sed "s%_CHANGE_PRODIR_%$projectDir%g
         s%_CHANGE_USERNAME_%$userName%g
         s%_CHANGE_IPV4_%$ipv4%g" "$f"> "${f/.template/}"

(Yes, that's a long double-quoted string spanning three physical lines.)

Update: I also changed the delimiter to % so that the substitution value can safely contain a slash. If you want to permit percent signs as well, you'll obviously have to come up with another delimiter still (colon, exclamation mark, semicolon are all popular).

Elliott Frisch · Accepted Answer · 2014-09-01 05:59:49Z

2

Well, I recommend you run the sed commands with -i for in-place, and surround your output file with "" so it supports files with spaces in the path and combining it into one sed invocation. That is something like,

cp "$f" "$toFile"
sed -i -e "s/_CHANGE_PRODIR_/$projectDir/g" \
       -e "s/_CHANGE_USERNAME_/$userName/g" \
       -e "s/_CHANGE_IPV4_/$ipv4/g" "$toFile"
# rm -f $f.bak
# rm -f $f.bak1
# rm -f $f.bak2

Also,

echo "> Your OS user name (e.g. peter):"
read userName

Might be

userName=$(whoami)

Depending on what you're using it for.

edited Sep 1, 2014 at 5:59

answered Sep 1, 2014 at 5:49

Elliott Frisch

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Comments

David C. Rankin · Accepted Answer · 2014-09-01 06:29:37Z

0

In addition to the other suggestions, one way to test/verify input in a more reliable manner is to convert the string data to lower-case and then limit the test to the substring you need:

echo "> Is this the project root directory? (y/n)"
read validProjectPath
ans="${validProjectPath,,}"         # conversion to lower-case
[ "${ans:0:1}" != "y" ] && exit 1   # test using compound-command

You can eliminate your .bakX file by using sed to 'edit-in-place' -i:

# setup
echo "prepare configuration files..."
for f in $(find "$projectDir/vagrant" -name "*.template" -type f); do 
    toFile=${f/.template/}
    cp "$f" "$toFile"
    sed -i "s/_CHANGE_PRODIR_/$projectDir/g" "$toFile"
    sed -i "s/_CHANGE_USERNAME_/$userName/g" "$toFile"
    sed -i "s/_CHANGE_IPV4_/$ipv4/g" "$toFile"
done

The only other thought (not recommendation) would be use readlink -f ${0} to return the calling script name and then parse for the path with either dirname or simple substring extraction ${fullname%/*}. What you have seem to work fine using BASH_SOURCE.

answered Sep 1, 2014 at 6:29

David C. Rankin

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1 Comment

tripleee Over a year ago

case $ans in [Yy]*) *;; *) exit 1;; esac avoids the case conversion. Matter of taste I suppose.

John B · Accepted Answer · 2014-09-01 10:17:19Z

Instead of creating unnecessary temporary files, you can use awk with gsub to do global replacement of a file.

for f in $(find "$projectDir/vagrant" -name "*.template" -type f); do
    toFile=${f%.template}
    awk -v p="$projectDir" -v u="$userName" -v ip=$ipv4 '{
        gsub("_CHANGE_PRODIR_", p)
        gsub("_CHANGE_USERNAME_", u)
        gsub("_CHANGE_IPV4_", ip)
    }' "$f" > "$toFile"
done

It might be better not to rely on the user having the VM IP address memorized. An array of possible IP addresses can be created using awk:

ips=($(awk '{
        m=match($0,/[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}/,a)
        if(m && a[0] !~ /^127./)
            print a[0]
    }' < <(ifconfig)
))

Then, a select loop can be used for the user to select the IP from a list.

echo "Select the VM IPv4 address:"
select opt in ${ips[@]}; do
    case $opt in
        ${ips[0]})
            ipv4=$opt
            break
            ;;
        ${ips[1]})
            ipv4=$opt
            break
            ;;
        ${ips[2]})
            ipv4=$opt
            break
            ;;
       *)
           echo invalid option
           ;;
    esac
done

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