[SOLVED] bash script trying to remove a leading ' and a tailing '

spartiati · 03-28-2010, 09:01 PM

I have a script that calls for a file description on a core file. I then pull the name of the process that caused the core file.
unfortunately, the process name is pulled with a leading ' amd a tailing'. I would like to remove the leading char and the last char.

code:
VAR=`file /tmp/core.1432 | awk '{ print $14}'`
echo "Process Name: $VAR"

output:
Process Name: 'ProcessName'

Results I need:
Process Name: ProcessName

I tried sed, but it seems to not like using the special char '.

I would appreciate any help on this.

grail · 03-28-2010, 10:26 PM

Code:

VAR=`file /tmp/core.1432 | awk '{ gsub(/\047/,"",$14); print $14}'`

catkin · 03-28-2010, 11:08 PM

Or it can be done entirely in the shell (which is a lot faster than using external commands) using Shell Parameter Expansion and Arithmetic Expansion

Code:

VAR=${VAR:1:$((${#VAR}-1))}

Peeling that onion from the inside out:

${#VAR} is the length of $VAR.
$(( )) gives a string which is the value of the arithmetic expression inside it, in this case the length of $VAR less one.
${VAR:S:L} gives the substring of $VAR starting at S and continuing for L characters.

Olion · 03-29-2010, 01:04 AM

Hi,

escape all metacharacter in the file using sed or

printf '%s' "$VAR"

Oleg

catkin · 03-29-2010, 01:19 AM

Quote:

Originally Posted by Olion

printf '%s' "$VAR"

Have I misunderstood? It doesn't seem to work:

Code:

c@CW8:~$ VAR="'ProcessName'"
c@CW8:~$ printf '%s' "$VAR"
'ProcessName'

dive · 03-29-2010, 01:25 AM

VAR=${VAR:1:$((${#VAR}-2))} works

Olion · 03-29-2010, 02:05 AM

Quote:

Originally Posted by catkin

Have I misunderstood? It doesn't seem to work:

Code:

c@CW8:~$ VAR="'ProcessName'"
c@CW8:~$ printf '%s' "$VAR"
'ProcessName'

O, sorry, I have misunderstood. I thought you need the ''.

Olion · 03-29-2010, 02:16 AM

again :-)

Code:

$ line="'Process'"
$ echo $line
'Process'
$ echo $line | tr -d "\'"
Process
$

David the H. · 03-29-2010, 02:30 AM

Olion's version above works only if you can be sure that the ' will not appear anywhere else in the string, as it simply removes any and all marks it finds. But here again parameter substitution can do it faster and more efficiently than piping it through an external tool.

Code:

VAR="${VAR//\'}"

Otherwise, Catkin's version is probably the best, for the same reasons.

catkin · 03-29-2010, 02:30 AM

Quote:

Originally Posted by dive

VAR=${VAR:1:$((${#VAR}-2))} works

Thanks for the correction

grail · 03-29-2010, 02:35 AM

David made me rethink too as I have done the same by removing all

Code:

VAR=`file /tmp/core.1432 | awk '{ gsub(/^\047+|\047+$/,"",$14); print $14}'`

ghostdog74 · 03-29-2010, 03:04 AM

Quote:

Originally Posted by spartiati

I have a script that calls for a file description on a core file. I then pull the name of the process that caused the core file.
unfortunately, the process name is pulled with a leading ' amd a tailing'. I would like to remove the leading char and the last char.

code:
VAR=`file /tmp/core.1432 | awk '{ print $14}'`
echo "Process Name: $VAR"

output:
Process Name: 'ProcessName'

Results I need:
Process Name: ProcessName

I tried sed, but it seems to not like using the special char '.

I would appreciate any help on this.

Code:

VAR=$(file /tmp/core.1442)
echo ${VAR//\'}
VAR=${VAR//\'}

colucix · 03-29-2010, 03:09 AM

Quote:

Originally Posted by spartiati

I tried sed, but it seems to not like using the special char '.

I second the suggested solutions that use parameter substitution in BASH, anyway using sed you can do

Code:

echo $VAR | sed "s/'//g"

as you can see, using single quotes to embed the sed command is not mandatory. In this case you have to protect the single quote from bash and double quotes perform their job perfectly.

Olion · 03-29-2010, 04:13 AM

Quote:

Originally Posted by colucix

I second the suggested solutions that use parameter substitution in BASH, anyway using sed you can do

Code:

echo $VAR | sed "s/'//g"

as you can see, using single quotes to embed the sed command is not mandatory. In this case you have to protect the single quote from bash and double quotes perform their job perfectly.

Thank you.
And for last word on the line:

$ cat x
ProcessName: 'Process'
$ sed "s/ '$[^ ][^ ]*$' *$/ \1/" x
ProcessName: Process
$

Olion · 03-29-2010, 04:56 AM

Code:

VAR="${VAR//\'}"

This is cool, but not working with my shell. I use /bin/sh :-(

Oleg