Sponsored Content
Full Discussion: False positive grep?
Top Forums Shell Programming and Scripting False positive grep? Post 303045879 by Chubler_XL on Thursday 16th of April 2020 05:55:04 PM
Old 04-16-2020
I do remember you being quite concerned with performance in this SWARM stuff and I would have thought the bash =~ operator could be use in place of grep.

Code:
$ export NUM='[['
$ time bash -c 'echo "$NUM" | grep -q "^\[\[" && echo yes'
yes

real    0m0.200s
user    0m0.000s
sys     0m0.107s
$ time bash -c '[[ "$NUM" =~ ^\[\[ ]] && echo yes'
yes

real    0m0.099s
user    0m0.015s
sys     0m0.046s

Twice as fast on my system, but your mileage may vary
This User Gave Thanks to Chubler_XL For This Post:
 

8 More Discussions You Might Find Interesting

1. Linux

bin\false

We have requirments to not allow a userid login abilities but allow users to 'su' to it. In solaris I normally set the shell in /etc/passwd to bin/false. THis does not work on Linux, any suggestions would help. (1 Reply)
Discussion started by: bryanthomas
1 Replies

2. Shell Programming and Scripting

false use of sed???

i want to delete every newline and every line which starts with "RECORD......." in a file. FILE: Record 61391 in base BROCKHAUS (Timestamp: 2008-04-09 11:38:38) UNTERTITEL : Gräfin (seit 1707 Reichsgräfin) von, * Schwerin 4. 2. 1686, + Berlin 21. 10. 1744; wurde Record 61392 in base BROCKHAUS... (4 Replies)
Discussion started by: trek
4 Replies

3. Shell Programming and Scripting

Why is it always false?

Hi, I'm new to UNIX and am trying to learn shell scripting in order to work on an interface that I inherited when a co-worker left. I need to be able to check to see whether a file exists to determine whether the FTP has taken place, but in testing, the if statement always evaluates as false,... (3 Replies)
Discussion started by: JeffR
3 Replies

4. Shell Programming and Scripting

False Condition

Hi All, I am using the below Script to enter a line in the File: #!/bin/ksh # To delete the last line if it contains the pattern Redirect permanent / Virgin Atlantic Airways - Popup echo "Enter the URL that should point to the particular microsite" read url # To delete the last line if it... (0 Replies)
Discussion started by: Shazin
0 Replies

5. IP Networking

false tcp connection

Why this happens? How to solve this? $netstat -na |grep 9325 tcp 0 0 127.0.0.1:9325 127.0.0.1:9325 ESTABLISHED When a client socket repeatedly tries to connect to an inactive(no server socket is listening on this port) local port,connect succeeds. ... (1 Reply)
Discussion started by: johnbach
1 Replies

6. AIX

Gid=0 and 7 + admin=FALSE

Checking configuration access files for an AIX server, left me wondering about this :confused:: If a user is added to system group, it gets gid=0 with some security risks because it gets some root kind of file access level. Is this insecure condition kept if the user has admin variable... (0 Replies)
Discussion started by: bkiddo
0 Replies

7. UNIX for Dummies Questions & Answers

Tail with positive offset

I have read the below from the book bash cookbook.Tail +1 filenames is similar to cat filename I have tried the same in Ubuntu 11.10 with bash. 4.0 . I have received error for the Same. May I know in which system that will work fine ? Thanks (1 Reply)
Discussion started by: pandeesh
1 Replies

8. Shell Programming and Scripting

False alerts

Hi I have written a script to send email alerts when load of my linux server reaches max point I keep getting false emails thought the load is normal , looks like same email is generated again and again - called from cron tab checked if the tempfile is present , no it is not , cleaned... (22 Replies)
Discussion started by: anil529
22 Replies
LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME
libbash -- A bash shared libraries package. DESCRIPTION
libbash is a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may want to load and use in scripts of your own. It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries. Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1). A bash shared library that can be loaded using ldbash(1) must answer 4 requirments: 1. It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash). 2. It must contain a line that begins with '#EXPORT='. That line will contain (after the '=') a list of functions that the library exports. I.e. all the function that will be usable after loading that library will be listed in that line. 3. It must contain a line that begins with '#REQUIRE='. That line will contain (after the '=') a list of bash libraries that are required for our library. I.e. every bash library that is in use in our bash library must be listed there. 4. The library must be listed (For more information, see ldbashconfig(8)). Basic guidelines for writing library of your own: 1. Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions. 2. Try to declare all variables intended for internal use as local. 3. Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with: __<library_name>_ For example, internal function myfoosort of hashstash library should be named as __hashstash_myfoosort This helps to avoid conflicts in global name space when using libraries that come from different vendors. 4. See html manual for full version of this guide. AUTHORS
Hai Zaar <haizaar@haizaar.com> Gil Ran <ril@ran4.net> SEE ALSO
ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1) Linux Epoch Linux
All times are GMT -4. The time now is 10:24 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy