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Top Forums Shell Programming and Scripting Using sed to change values after a specific string Post 302958342 by prodigious8 on Wednesday 21st of October 2015 11:18:05 AM
Old 10-21-2015
Using sed to change values after a specific string

Hello I have a script that searches a file for a specific string and then changes the nth column after that string. I have searched online for how to do this with sed but have not seemed to find a solution that works for me. I am using bash.

Some background info:
- Currently I am using awk to do this successfully.
- I was informed that sed with --in place set would be faster

the awk command I use is as follows

Code:
site='SITES'
mx=50
awk -v n="$site" -v a="$mx" '$1==n{$2=a}{print $0}' FS=' ' OFS=' ' $FILENAME &> tmp && mv tmp $FILENAME

What this does is finds the line where 'SITES' is written in the file (a label for that row) then changes the second element (column) of that row to mx (which is 50).

1. I want to know if its true that using sed will be faster (considering this is looped for thousands of files)
2. Also want to know how to implement with sed if thats the case. So far I have tried (and failed) the following:
Code:
sed -i {$site}'/s/\S\+/'"${mx}"'/2' $FILENAME

I think there might be a misconception that sed is faster and from what I researched awk is the better option. The person who told me sed is faster has much more experience than me but I have a feeling he is incorrect.

Last edited by prodigious8; 10-21-2015 at 03:38 PM..
 

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LOGPROF.CONF(5) 						     AppArmor							   LOGPROF.CONF(5)

NAME
logprof.conf - configuration file for expert options that modify the behavior of the AppArmor aa-logprof(1) program. DESCRIPTION
The aa-logprof(1) program can be configured to have certain default behavior by the contents of logprof.conf. The [qualifiers] section lists specific programs that should have a subset of the full ix/px/ux list when asking what mode to execute it using. Since creating a separate profile for /bin/bash is dangerous, we can specify that for /bin/bash, only (I)nherit, (U)nconstrained, and (D)eny should be allowed options and only those will show up in the prompt when we're asking about adding that to a profile. Likewise, if someone currently exec's /bin/mount in ix or px mode, things won't work, so we can provide only (U)nconstrained and (D)eny as options. And certain apps like grep, awk, sed, cp, and mkdir should always inherit the parent profile rather than having their own profile or running unconfined, so for them we can specify that only (I)nherit and (D)eny are the allowed options. Any programs that are not listed in the qualifiers section get the full (I)nherit / (P)rofile / (U)nconstrained / (D)eny option set. If the user is doing something tricky and wants different behavior, they can tweak or remove the corresponding line in the conf file. The [defaulthat] section lists changehat-aware programs and what hat aa-logprof(1) will collapse the entries to for that program if the user specifies that the access should be allowed, but should not have it's own hat. The [globs] section allows modification of the logprof rule engine with respect to globbing suggestions that the user will be prompted with. The format of each line is-- "<perl glob> = <apparmor glob>". When aa-logprof(1) asks about a specific path, if the perl glob matches the path, it replaces the part of the path that matched with the corresponding apparmor glob and adds it to the list of globbing suggestions. Lines starting with # are comments and are ignored. EXAMPLE
[qualifiers] # things will very likely be painfully broken if bash has it's own profile /bin/bash = iu # mount doesn't work if it's confined /bin/mount = u # these helper utilities should inherit the parent profile and # shouldn't have their own profiles /bin/awk = i /bin/grep = i /bin/sed = i [defaulthat] /usr/sbin/sshd = EXEC /usr/sbin/httpd2 = DEFAULT_URI /usr/sbin/httpd2-prefork = DEFAULT_URI [globs] # /foo/bar/lib/libbaz.so -> /foo/bar/lib/lib* /lib/lib[^/]+so[^/]*$ = /lib/lib*so* # strip kernel version numbers from kernel module accesses ^/lib/modules/[^/]+/ = /lib/modules/*/ # strip pid numbers from /proc accesses ^/proc/d+/ = /proc/*/ BUGS
If you find any bugs, please report them at <http://https://bugs.launchpad.net/apparmor/+filebug>. SEE ALSO
apparmor(7), apparmor.d(5), aa-enforce(1), aa-complain(1), aa-disable(1), aa_change_hat(2), aa-logprof(1), aa-genprof(1), and <http://wiki.apparmor.net>. AppArmor 2.7.103 2012-06-28 LOGPROF.CONF(5)
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