need help with a bash script

smeezekitty · 10-06-2009, 06:00 PM

first thing this is not homework
ok i got a file laid out like this
[code]
00:00:01.871 <bla> <bla> <bla>
00:00:02.665 <bla> <bla> <bla>
09:15:34.003 <bla> <bla> <bla>
[code]
i want to set the forth number of evrey line to zero
all in a bash script
is it possable?

lutusp · 10-06-2009, 06:32 PM

Quote:

Originally Posted by smeezekitty

first thing this is not homework
ok i got a file laid out like this
[code]
00:00:01.871 <bla> <bla> <bla>
00:00:02.665 <bla> <bla> <bla>
09:15:34.003 <bla> <bla> <bla>
[code]
i want to set the forth number of evrey line to zero
all in a bash script
is it possable?

The what number? Give a specific example:

I have this as an input ___________________

I want this as an output __________________

Leave nothing to the imagination.

smeezekitty · 10-06-2009, 06:36 PM

input 00:00:01.555
output 00:00:01.000
--or--
input 01:32:15.003
output 01:32:15.000

lutusp · 10-06-2009, 08:07 PM

Quote:

Originally Posted by smeezekitty

input 00:00:01.555
output 00:00:01.000
--or--
input 01:32:15.003
output 01:32:15.000

Code:

$ x="00:00:01.555"
$ echo ${x%%.*}.000
00:00:01.000

I have a tutorial on my Website that covers this sort of thing:

Bash Shell Programming in Linux

smeezekitty · 10-06-2009, 08:14 PM

not quite right
here is some example text from the file

Code:

00:00:01.879   Trusted       <integer> = 0x0000000000000001 (1)
00:00:01.879   PCIDeviceNo   <integer> = 0x0000000000000001 (1)
00:00:01.879   PCIFunctionNo <integer> = 0x0000000000000001 (1)
00:00:01.879 
00:00:01.879 [/Devices/piix3ide/0/Config/] (level 4)
00:00:01.880   Type <string>  = "PIIX4" (cch=6)
         ^^^
         \|/
          V
          |_this needs to be changed to zero on every line

vonbiber · 10-07-2009, 01:51 AM

Quote:

Originally Posted by smeezekitty

not quite right
here is some example text from the file

Code:

00:00:01.879   Trusted       <integer> = 0x0000000000000001 (1)
00:00:01.879   PCIDeviceNo   <integer> = 0x0000000000000001 (1)
00:00:01.879   PCIFunctionNo <integer> = 0x0000000000000001 (1)
00:00:01.879 
00:00:01.879 [/Devices/piix3ide/0/Config/] (level 4)
00:00:01.880   Type <string>  = "PIIX4" (cch=6)
         ^^^
         \|/
          V
          |_this needs to be changed to zero on every line

lustup gave you the command based on the input from your previous
message. Now you can use the same idea with the full line
Say your input file is input.txt and you want to output to output.txt
then you could

Code:

rm -f output.txt
cat input.txt | while read line
do
    x=$(echo $line | awk '{print $1}'
    y=${x%%.*}.000
    #new line is eg: '00:00:01.000'
    #followed by '   Trusted       <integer> = 0x0000000000000001 (1)'
    newline=${y}"$(echo $line | sed 's?^[^ \t]*??')"
    echo "$newline" >> output.txt
done

lutusp · 10-07-2009, 02:23 AM

Quote:

Originally Posted by smeezekitty

not quite right
here is some example text from the file

Code:

00:00:01.879   Trusted       <integer> = 0x0000000000000001 (1)
00:00:01.879   PCIDeviceNo   <integer> = 0x0000000000000001 (1)
00:00:01.879   PCIFunctionNo <integer> = 0x0000000000000001 (1)
00:00:01.879 
00:00:01.879 [/Devices/piix3ide/0/Config/] (level 4)
00:00:01.880   Type <string>  = "PIIX4" (cch=6)
         ^^^
         \|/
          V
          |_this needs to be changed to zero on every line

Quote:

not quite right

Not explained quite right. Try this:

Code:

while read line
do
    echo ${line/.[0-9][0-9][0-9]/.000}
done

Result:

Code:

00:00:01.000   Trusted       <integer> = 0x0000000000000001 (1)
00:00:01.000   PCIDeviceNo   <integer> = 0x0000000000000001 (1)
00:00:01.000   PCIFunctionNo <integer> = 0x0000000000000001 (1)
00:00:01.000
00:00:01.000 [/Devices/piix3ide/0/Config/] (level 4)
00:00:01.000   Type <string>  = "PIIX4" (cch=6)

gnashley · 10-07-2009, 10:29 AM

lutusp, I wne to look at your tutorial right away, but I was a little disappointed...
You spent many lines teaching things which are not bas at all:
date
whoami
ls
find
tree
file
cat
more
grep
wc
But, the worst mistake is confusing /bin/test with the bash builtin test and several other builtin commands:
'man test' wil give you the man-page for /usr/bin/test
But, if you use simply 'test' in the shell, you'll be using bash's builtin test which is not the same. Same goes for cd, pwd and [ (or [[.

Use 'type test' to discover whether your 'test' is a builtin. If you use 'which test' you'll get /usr/bin/test, but 'type test' will tell you that test is a bash builtin. So, the real way to get help for the 'test' command is to use 'help test' and the same for the others.

smeezekitty · 10-07-2009, 12:02 PM

@vonbiber

Code:

bash-2.04$ rmv.sh
./rmv.sh: line 4: unexpected EOF while looking for matching `)'
./rmv.sh: line 11: syntax error: unexpected end of file
bash-2.04$

Disillusionist · 10-07-2009, 12:34 PM

Alternative using sed:

Code:

sed -i 's/\.[0-9][0-9][0-9]/\.000/' file

Make sure you have a backup of the original file while testing that it doesn't have any unforseen issues.

catkin · 10-07-2009, 12:52 PM

Quote:

Originally Posted by smeezekitty

@vonbiber

Code:

bash-2.04$ rmv.sh
./rmv.sh: line 4: unexpected EOF while looking for matching `)'
./rmv.sh: line 11: syntax error: unexpected end of file
bash-2.04$

Bash said the problem was on line 4; a closing ) is needed after $line.

smeezekitty · 10-07-2009, 01:11 PM

Code:

./rmv.sh: cat: Too many open files (EMFILE)

oh great

gnashley · 10-07-2009, 02:56 PM

smeezekitty, I notice you are using bash-2.04. That may have some bearing on any problems as it lacks certain features available in later versions. If you really need to use bash-2.04, you might want to put #!/bin/sh as the shebang instead of #!/bin/bash and then just try to make it all POSIX-compatible instead of using bashisms.

konsolebox · 10-08-2009, 01:33 AM

assuming index starts with 0:

Code:

#!/bin/bash

IF=$1 OF=$2

{
	while read LINE; do
		echo "${LINE:0:9}0${LINE:12}"
	done
} < "$IF" > "$OF"

or

Code:

#!/bin/bash

IF=$1 OF=$2

shopt -s extglob

{
	while read LINE; do
		A=${LINE:0:9}
		B=${LINE:9}
		B=${B##+([[:digit:]])}
		echo "${A}0${B}"
	done
} < "$IF" > "$OF"

sometimes, {} is no longer needed but it's more consistent, i think

lutusp · 10-08-2009, 03:24 AM

Quote:

Originally Posted by gnashley

lutusp, I wne to look at your tutorial right away, but I was a little disappointed...
You spent many lines teaching things which are not bas at all:

The title of the article is "Bash Shell Programming in Linux". Nowhere does it say or require that all the discussed commands are built-ins. That isn't the point. The point is for newbies to learn how to get results using a Bash shell session, not to limit themselves to Bash built-ins.