Bash -- last output?

nrg · 11-19-2009, 02:50 PM

I couldn't find this documented, probably because I don't know the command.

I'm trying to get the last outputted line, AFTER the fact.

For example:

Code:

$ which bash
/usr/bin/bash

$

What command can I execute to get the string "/usr/bin/bash" from the previous result (without rerunning 'which bash')

Komakino · 11-19-2009, 02:59 PM

Quote:

Originally Posted by nrg

I couldn't find this documented, probably because I don't know the command.

I'm trying to get the last outputted line, AFTER the fact.

For example:

Code:

$ which bash
/usr/bin/bash

$

What command can I execute to get the string "/usr/bin/bash" from the previous result (without rerunning 'which bash')

What do you want to do with it after you've got it?

GrapefruiTgirl · 11-19-2009, 03:02 PM

sasha@reactor:~$ hello=$(which bash)
sasha@reactor:~$ echo $hello
/usr/bin/bash
sasha@reactor:~$

nrg · 11-19-2009, 03:10 PM

Quote:

Originally Posted by Komakino

What do you want to do with it after you've got it?

This is going to be used on a large 'ant build' output -- it's quite common that resources aren't updated in the build.xml, so I'll get an error such as:

Code:

BUILD FAILED
c:\app\trunk\build.xml:90: Error while expanding c:\app\trunk\resolved-lib\resource-1.1.jar
java.io.FileNotFoundException: c:\app\trunk\resolved-lib\resource-1.1.jar (The system cannot find the file specified)

My plan is to take the last output (java.io.FileNotFoundException: c:\app\trunk\resolved-lib\resource-1.1.jar (The system cannot find the file specified)) and extract the resource name, then 'find' the updated file (in this case, would be something like 'resource-1.2.jar') in resolved-lib, and transfer the new version number to the build.xml.

The build.xml line:

Code:

<unzip src="${ivy.resolved.lib.dir}/resource-1.1.jar" dest="${classes.dir}" />

nrg · 11-19-2009, 03:13 PM

It might actually be better to grep the build.xml file beforehand, and check for inconsistencies in the resolved-lib, so it wouldn't fail in the first place... I think I'll do that instead

david1941 · 11-19-2009, 03:17 PM

How about sending STDOUT to fileout and using $(tail -1 fileout) for the requested line?

nrg · 11-19-2009, 06:40 PM

Alright, I've written the script to parse through the build.xml and update it based on the files in the resolved-lib, the only problem I have now seems to be permission-based.

Code:

perl -p -i -e 's/resource-1.0.jar/resource-1.1.jar/g' ./build.xml

and

Code:

sed -i 's/resource-1.0.jar/resource-1.1.jar/g' ./build.xml

don't work when run in the .sh file, but works perfectly fine when I run it manually.

Any ideas?

Here's the full file, please go easy on me if I did something horribly wrong, haven't been doing this for very long

Code:

#!/bin/bash

buildfile="build.xml"

grep "unzip src=\"\${ivy" $buildfile | while read line; do
	fullname=$(echo $line|perl -pe 's/.+\/(.*?)".+/\1/')
	if [ -e ./resolved-lib/$fullname ]; then
		echo "found $fullname"
	else
		echo "$fullname not found"
		rootname=$(echo $fullname|perl -pe 's/(.+)-[0-9].+/\1-/')
		if [ -e ./resolved-lib/$rootname* ]; then
			newname=$(echo ./resolved-lib/$rootname*|perl -pe 's/.+\/(.+)/\1/')
			echo "GOT IT! $newname"
			perl -p -i -e 's/$fullname/$newname/g' ./$buildfile
			echo "perl -p -i -e 's/$fullname/$newname/g' ./$buildfile"
		else
			echo "$rootname not found"
			read #pause
		fi
	fi
done

nrg · 11-19-2009, 06:59 PM

even after I chmod build.xml to 777 (within the .sh, and it works) it doesn't update the file. Notepad++ is detecting a modification, but it's not actually changing the text

nrg · 11-19-2009, 07:35 PM

Ahh, the problem was the variables weren't working... changing the apostrophes to quotes worked, as such:

Code:

sed -i "s/$fullname/$newname/g" build.xml