bash grep help

[Ed_P]

If the command "cat /proc/cmdline" returns a "from=" operand how does one extract the file name that follows it?

FileName=`cat /proc/cmdline`
echo "Boot File: ${FileName:17:36}"

Works if the filename is 36 characters but that isn't always the case. I've looked into using grep but have failed so far.

[aus9]

Ed_P

I am an intermediate coder so until you get a better reply I hope you don't mind me asking questions and making comments?

1) Can you show the actual output of these 2 commands please

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cat /proc/cmdline

echo $MODDIR

The reason why I ask is your second line does not appear to be relative to your first line.
I was expecting your second line to read something like .....
echo $FileName | grep something or
VARIABLE2=`echo $FileName | grep something`

but maybe you are trying to write a script?

I don't know just guessing

good luck

[donald]

not using grep but sed to get the Filename
Try:

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cat /proc/cmdline | sed -e 's/^.*from=//' -e 's/ .*$//'

The first expression removes from= and everything before.
The second one removes the next space and everything after.

more info about sed
http://linux.die.net/man/1/sed

[Bogomips]

Bashing along:

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guest@porteus:~$ c=$(cat /proc/cmdline); f=${c#*from=}; f=${f%% *}
guest@porteus:~$ echo $f
/tmp/iso/Por-KDE4-v3.1-4.2.5-i486.iso

@donald Nice link.

[Ed_P]

Wow!!!

Thank you all.

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guest@porteus:~$ cat /proc/cmdline
quiet from=/ISOs/Porteus-RazorQT-v3.0.1-x86_64-nu.iso changes=EXIT:/porteus3.0/changes/porteussave.dat extramod=/porteus3.0/Modules volume=40 reboot=cold ramsize=80%
guest@porteus:~$ echo $MODDIR

guest@porteus:~$ cat /proc/cmdline | sed -e 's/^.*from=//' -e 's/ .*$//'
/ISOs/Porteus-RazorQT-v3.0.1-x86_64-nu.iso
guest@porteus:~$ c=$(cat /proc/cmdline); f=${c#*from=}; f=${f%% *}
guest@porteus:~$ echo $f
/ISOs/Porteus-RazorQT-v3.0.1-x86_64-nu.iso
guest@porteus:~$ 

But the part that really blows my mind are the special character strings. c#* %% * s/^. s/.*$// Where did these come from??? The closest I remember seeing something close is here: http://forum.porteus.org/viewtopic.php? ... =30#p28468

-update-

And now I have:

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guest@porteus:~$ bootdev.sh
Boot device: /dev/sda5
Device format: "ntfs" 
Boot ISO:  /ISOs/Porteus-RazorQT-v3.0.1-x86_64-nu.iso
 Changes are being saved to a save.dat file.
Save.dat file: /porteus3.0/changes/porteussave.dat
Cmdline: quiet from=/ISOs/Porteus-RazorQT-v3.0.1-x86_64-nu.iso changes=EXIT:/porteus3.0/changes/porteussave.dat extramod=/porteus3.0/Modules volume=40 reboot=cold ramsize=80%
guest@porteus:~$ 

[Bogomips]

But the part that really blows my mind are the special character strings. c#* %% * s/^. s/.*$// Where did these come from???

c#* %% *

http://man.cx/bashFind(^F): ##

s/^. s/.*$

http://manpages.ubuntu.com/manpages/pre ... gex.7.html

[Ed_P]