sed escapes

[jpeps]

It seems worth the work to create an "escape" script that does all the changes to a string. Then any script that needs to not have a character taken to be a special character can use it. This would be like the thing in JavaScript.

Here's one I'm testing using Bash string manipulation:

Code: Select all

#!/bin/bash 

### SED script

VAR="$1"

   VAR="${VAR//\/\\}"
   VAR="${VAR//\//\/}"
   VAR="${VAR//\*/\*}"
   VAR="${VAR//\[/\[}"
   VAR="${VAR//\]/\]}"
   VAR="${VAR//\-/\-}"
   VAR="${VAR//\^/\^}"

 echo "$VAR"

Example:

VAR="/usr/bin/myfile-2.1[34]"
FILE=`SED "$VAR"`
sed "/${FILE}/d" ./list

[Moose On The Loose]

It seems worth the work to create an "escape" script that does all the changes to a string. Then any script that needs to not have a character taken to be a special character can use it. This would be like the thing in JavaScript.

Here's one I'm testing using Bash string manipulation:

Code: Select all

#!/bin/bash 

### SED script

VAR="$1"

   VAR="${VAR//\/\\}"
   VAR="${VAR//\//\/}"
   VAR="${VAR//\*/\*}"
   VAR="${VAR//\[/\[}"
   VAR="${VAR//\]/\]}"
   VAR="${VAR//\-/\-}"
   VAR="${VAR//\^/\^}"

 echo "$VAR"

Example:

VAR="/usr/bin/myfile-2.1[34]"
FILE=`SED "$VAR"`
sed "/${FILE}/d" ./list

How about this

Code: Select all

# echo "This-is+a*string" | sed "s/\([-+*.]\)/\\\\\1/g"

It can replace several special characters in one go.

[jpeps]

How about this

Code: Select all

# echo "This-is+a*string" | sed "s/\([-+*.]\)/\\\\\1/g"

It can replace several special characters in one go.

I had tried (something like) that, but didn't seem to work, although there's probably a way. Anyway, sed is slower and I couldn't get it to handle something like "" even though \\ is supposed to work.

edit: Found the problem.

echo "$VAR" | sed "s/\([-+*.]\)/\\\\\1/g"
This\-is\+a\*string

VAR=`"$VAR" | sed "s/\([-+*.]\)/\\\\\1/g"`
This\1is\1a\1string

[seaside]

Interesting....

This works-

Code: Select all

 VAR=$(echo "This-is+a*string" | sed "s/\([-+*.]\)/\\\\\1/g")
# echo $VAR
This\-is\+a\*string

[jpeps]

editing....

Back to using "$()" !!!

Sed doesn't recognize \+, so have to delete that from the script. The bash-replacement ran over 20% faster even with all the extra searches (I averaged over 5 trials for each).

[seaside]

editing....

Back to using "$()" !!!

Sed doesn't recognize \+, so have to delete that from the script. The bash-replacement ran over 20% faster even with all the extra searches (I averaged over 5 trials for each).

jpeps,

Is there a bash script to delete lines matching an expression that doesn't have to rewrite the file and runs faster than Sed or it does it run faster even though it rewrites?

Regards,
s

[jpeps]

editing....

Back to using "$()" !!!

Sed doesn't recognize \+, so have to delete that from the script. The bash-replacement ran over 20% faster even with all the extra searches (I averaged over 5 trials for each).

jpeps,

Is there a bash script to delete lines matching an expression that doesn't have to rewrite the file and runs faster than Sed or it does it run faster even though it rewrites?

Regards,
s

Hi seaside,
I'm just deleting a matched filename from a /tmp list that gets used to build a targz. I added a timer to a test script that didn't actually delete anything (sed vs sed -i). The only difference was the SED script, which used sed vs bash string manipulation.

Edit: actually there's quite a large standard deviation. Running more tests shrank the difference to almost nothing....and we're only talking milliseconds.

[Moose On The Loose]

editing....

Back to using "$()" !!!

Sed doesn't recognize \+, so have to delete that from the script. The bash-replacement ran over 20% faster even with all the extra searches (I averaged over 5 trials for each).

jpeps,

Is there a bash script to delete lines matching an expression that doesn't have to rewrite the file and runs faster than Sed or it does it run faster even though it rewrites?

Regards,
s

Is there a way to make bash do more than one item?

Code: Select all

# AA="-----"
# echo "${AA/-/\\-}"
\-----

It seems very ugly to have to code a loop or something

[technosaurus]

echo ${A//-/\\-/}
\-/\-/\-/\-/\-/

[Moose On The Loose]

echo ${A//-/\\-/}
\-/\-/\-/\-/\-/

Yes, that does it nicely.
This allows us to make a more general version if needed

Code: Select all

 AA="++++///---"
# Z="+"
# echo ${AA/${Z}/\\${Z}}
\++++///---
# echo ${AA//${Z}/\\${Z}}
\+\+\+\+///---
# 

[jpeps]

echo ${A//-/\\-/}
\-/\-/\-/\-/\-/

Yes, that does it nicely.

...which is the script I already posted.