Sponsored Content
Full Discussion: Noob trying to improve
Operating Systems OS X (Apple) Noob trying to improve Post 302989490 by MadeInGermany on Friday 13th of January 2017 09:02:21 AM
Old 01-13-2017
local means: the variable exists only within the current scope.
In Bash: within the current function.
Bash is not a declarative language, and has loose type binding.
For example you can add a 1 to a string "5", and get "51" or 6 dependent on the operator.
With declare -i you can limit the misuse of variables. For example
Code:
i="a"; [ $i -lt 5 ] && echo "$i is less than 5"

gives a syntax error. With declare -i i the "a" will be casted to a 0, and there will not be a syntax error (but might still result in a malfunction in the following code).
declare makes most sense for special variables like arrays.
This User Gave Thanks to MadeInGermany For This Post:
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Can I improve this script ???

Hi all, Still a newbie and learning as I go ... as you do :) Have created this script to report on disc usage and I've just included the ChkSpace function this morning. It's the first time I've read a file (line-by-bloody-line) and would like to know if I can improve this script ? FYI - I... (11 Replies)
Discussion started by: Cameron
11 Replies

2. UNIX for Advanced & Expert Users

improve performance by using ls better than find

Hi , i'm searching for files over many Aix servers with rsh command using this request : find /dir1 -name '*.' -exec ls {} \; and then count them with "wc" but i would improve this search because it's too long and replace directly find with ls command but "ls *. " doesn't work. and... (3 Replies)
Discussion started by: Nicol
3 Replies

3. Shell Programming and Scripting

improve this?

Wrote this script to find the date x days before or after today. Is there any way that this script can be speeded up or otherwise improved? #!/usr/bin/sh check_done() { if then daysofmth=31 elif then if ... (11 Replies)
Discussion started by: blowtorch
11 Replies

4. UNIX for Dummies Questions & Answers

Improve Performance

hi someone tell me which ways i can improve disk I/O and system process performance.kindly refer some commands so i can do it on my test machine.thanks, Mazhar (2 Replies)
Discussion started by: mazhar99
2 Replies

5. Shell Programming and Scripting

Any way to improve performance of this script

I have a data file of 2 gig I need to do all these, but its taking hours, any where i can improve performance, thanks a lot #!/usr/bin/ksh echo TIMESTAMP="$(date +'_%y-%m-%d.%H-%M-%S')" function showHelp { cat << EOF >&2 syntax extreme.sh FILENAME Specify filename to parse EOF... (3 Replies)
Discussion started by: sirababu
3 Replies

6. IP Networking

How to improve throughput?

I have a 10Gbps network link connecting two machines A and B. I want to transfer 20GB data from A to B using TCP. With default setting, I can use 50% bandwidth. How to improve the throughput? Is there any way to make throughput as close to 10Gbps as possible? thanks~ :) (3 Replies)
Discussion started by: andrewust
3 Replies

7. Shell Programming and Scripting

Want to improve the performance of script

Hi All, I have written a script as follows which is taking lot of time in executing/searching only 3500 records taken as input from one file in log file of 12 GB Approximately. Working of script is read the csv file as an input having 2 arguments which are transaction_id,mobile_number and search... (6 Replies)
Discussion started by: poweroflinux
6 Replies

8. AIX

improve sulog

I just wrote a very small script that improves readability on system sulog. The problem with all sulog is there is lack of clarity whether the info you are looking at is the most current. So if you just need a simple soution instead of going thru the trouble of writing a script that rotate logs and... (0 Replies)
Discussion started by: sparcguy
0 Replies

9. Shell Programming and Scripting

How to improve an script?

Gents. I have 2 different scripts for the same purpose: raw2csv_1 Script raw2csv_1 finish the process in less that 1 minute raw2csv_2 Script raw2csv_2 finish the process in more that 6 minutes. Can you please check if there is any option to improve the raw2csv_2. To finish the job... (4 Replies)
Discussion started by: jiam912
4 Replies

10. Shell Programming and Scripting

Improve script

Gents, Is there the possibility to improve this script to be able to have same output information. I did this script, but I believe there is a very short code to get same output here my script awk -F, '{if($10>0 && $10<=15) print $6}' tmp1 | sort -k1n | awk '{a++} END { for (n in a )... (23 Replies)
Discussion started by: jiam912
23 Replies
SED(1)								   User Commands							    SED(1)

NAME
sed - manual page for sed version 4.0.3 SYNOPSIS
sed [OPTION]... {script-only-if-no-other-script} [input-file]... DESCRIPTION
Sed is a stream editor. A stream editor is used to perform basic text transformations on an input stream (a file or input from a pipe- line). While in some ways similar to an editor which permits scripted edits (such as ed), sed works by making only one pass over the input(s), and is consequently more efficient. But it is sed's ability to filter text in a pipeline which particularly distinguishes it from other types of editors. -n, --quiet, --silent suppress automatic printing of pattern space -e script, --expression=script add the script to the commands to be executed -f script-file, --file=script-file add the contents of script-file to the commands to be executed -i[suffix], --in-place[=suffix] edit files in place (makes backup if extension supplied) -l N, --line-length=N specify the desired line-wrap length for the `l' command -r, --regexp-extended use extended regular expressions in the script. -s, --separate consider files as separate rather than as a single continuous long stream. -u, --unbuffered load minimal amounts of data from the input files and flush the output buffers more often --help display this help and exit -V, --version output version information and exit If no -e, --expression, -f, or --file option is given, then the first non-option argument is taken as the sed script to interpret. All remaining arguments are names of input files; if no input files are specified, then the standard input is read. E-mail bug reports to: bonzini@gnu.org . Be sure to include the word ``sed'' somewhere in the ``Subject:'' field. COMMAND SYNOPSIS
This is just a brief synopsis of sed commands to serve as a reminder to those who already know sed; other documentation (such as the tex- info document) must be consulted for fuller descriptions. Zero-address ``commands'' : label Label for b and t commands. #comment The comment extends until the next newline (or the end of a -e script fragment). } The closing bracket of a { } block. Zero- or One- address commands = Print the current line number. a text Append text, which has each embedded newline preceded by a backslash. i text Insert text, which has each embedded newline preceded by a backslash. q Immediately quit the sed script without processing any more input, except that if auto-print is not disabled the current pattern space will be printed. Q Immediately quit the sed script without processing any more input. r filename Append text read from filename. R filename Append a line read from filename. Commands which accept address ranges { Begin a block of commands (end with a }). b label Branch to label; if label is omitted, branch to end of script. t label If a s/// has done a successful substitution since the last input line was read and since the last t or T command, then branch to label; if label is omitted, branch to end of script. T label If no s/// has done a successful substitution since the last input line was read and since the last t or T command, then branch to label; if label is omitted, branch to end of script. c text Replace the selected lines with text, which has each embedded newline preceded by a backslash. d Delete pattern space. Start next cycle. D Delete up to the first embedded newline in the pattern space. Start next cycle, but skip reading from the input if there is still data in the pattern space. h H Copy/append pattern space to hold space. g G Copy/append hold space to pattern space. x Exchange the contents of the hold and pattern spaces. l List out the current line in a ``visually unambiguous'' form. n N Read/append the next line of input into the pattern space. p Print the current pattern space. P Print up to the first embedded newline of the current pattern space. s/regexp/replacement/ Attempt to match regexp against the pattern space. If successful, replace that portion matched with replacement. The replacement may contain the special character & to refer to that portion of the pattern space which matched, and the special escapes 1 through 9 to refer to the corresponding matching sub-expressions in the regexp. w filename Write the current pattern space to filename. W filename Write the first line of the current pattern space to filename. y/source/dest/ Transliterate the characters in the pattern space which appear in source to the corresponding character in dest. Addresses Sed commands can be given with no addresses, in which case the command will be executed for all input lines; with one address, in which case the command will only be executed for input lines which match that address; or with two addresses, in which case the command will be executed for all input lines which match the inclusive range of lines starting from the first address and continuing to the second address. Three things to note about address ranges: the syntax is addr1,addr2 (i.e., the addresses are separated by a comma); the line which addr1 matched will always be accepted, even if addr2 selects an earlier line; and if addr2 is a regexp, it will not be tested against the line that addr1 matched. After the address (or address-range), and before the command, a ! may be inserted, which specifies that the command shall only be executed if the address (or address-range) does not match. The following address types are supported: number Match only the specified line number. first~step Match every step'th line starting with line first. For example, ``sed -n 1~2p'' will print all the odd-numbered lines in the input stream, and the address 2~5 will match every fifth line, starting with the second. (This is an extension.) $ Match the last line. /regexp/ Match lines matching the regular expression regexp. cregexpc Match lines matching the regular expression regexp. The c may be any character. GNU sed also supports some special 2-address forms: 0,addr2 Start out in "matched first address" state, until addr2 is found. This is similar to 1,addr2, except that if addr2 matches the very first line of input the 0,addr2 form will be at the end of its range, whereas the 1,addr2 form will still be at the beginning of its range. addr1,+N Will match addr1 and the N lines following addr1. addr1,~N Will match addr1 and the lines following addr1 until the next line whose input line number is a multiple of N. REGULAR EXPRESSIONS
POSIX.2 BREs should be supported, but they aren't completely because of performance problems. The sequence in a regular expression matches the newline character, and similarly for a, , and other sequences. BUGS
E-mail bug reports to bonzini@gnu.org. Be sure to include the word ``sed'' somewhere in the ``Subject:'' field. Also, please include the output of ``sed --version'' in the body of your report if at all possible. COPYRIGHT
Copyright (C) 2002 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE, to the extent permitted by law. SEE ALSO
awk(1), ed(1), grep(1), tr(1), perlre(1), sed.info, any of various books on sed, the sed FAQ (http://sed.sf.net/grabbag/tutorials/sed- faq.html), http://sed.sf.net/grabbag/. The full documentation for sed is maintained as a Texinfo manual. If the info and sed programs are properly installed at your site, the command info sed should give you access to the complete manual. sed version 4.0.3 November 2002 SED(1)
All times are GMT -4. The time now is 07:14 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy