Sponsored Content
Top Forums Shell Programming and Scripting Need help with parameter expansion Post 302462334 by stevenswj on Thursday 14th of October 2010 02:09:46 AM
Old 10-14-2010
Need help with parameter expansion

Say you have this numeric variable that can be set by the user but you never want it to leave a certain range when it gets printed. How could you use parameter expansion such that it will never expand outside of that boundary? Thanks

---------- Post updated at 11:09 PM ---------- Previous update was at 10:57 PM ----------

Bah nevermind looks like the ternary operator is the answer and not parameter expansion

I was running this script every so many seconds using sleep but on the first attempt I didn't want it to sleep less than 60 seconds, but the user could specify higher. On subsequent attempts I didn't want the user to specify lower than 20s.

So for the first attempt I have something like:
Code:
sleep $(($frequency > 60 ? $frequency : 60))

and subsequent attempts:
Code:
sleep $(( $frequency > 20 ? $frequency : 20))

Moderator's Comments:
Mod Comment Please use code tags, thanks.

Last edited by zaxxon; 10-14-2010 at 03:26 AM..
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

removing html tags via parameter expansion

Hi all- I have a variable that contains a web page: echo $STUFF <html> <head> <title>my page</title></head> <body> blah blah etc.. Can I use the shell's parameter expansion abilities to remove just the tags? I thought that FIXHTML=${STUFF//<*>/} might do it, but it didn't seem to... (2 Replies)
Discussion started by: rev66
2 Replies

2. Shell Programming and Scripting

Need to print the expansion of the found string (the expansion is beween two delimiters '-' , '||'

Hi , could anyone help me out with this problem. sample.txt has this content : u001- this is used for project1 || u002- this is used for p2|| not to be printed u003- this is used for project3 || u004- this is used for p4 || u005- this is used for project5 || u006- this is used for p6... (9 Replies)
Discussion started by: Balaji PK
9 Replies

3. Shell Programming and Scripting

Bash parameter expansion from a config file

Hi - I am trying to do a simple config file with known variable names in it, e.g.: contents of config file a.conf: -a -b $work -c $host simplified contents of bash script file: work='trunk' host='alaska' opts=$(tr '\n' ' ' < a.conf) opts="$opts $*" mycommand $opts arg1 arg2 The... (3 Replies)
Discussion started by: mrengert
3 Replies

4. Shell Programming and Scripting

Parameter expansion not working for all strings...

I'm trying to write a script that parses my music collection and hard link some filenames that my media player doesn't like to other names. To do this I need to extract the name and remove alla non ASCII characters from that and do a cp -l with the result. Problem is this: 22:16:58 $... (8 Replies)
Discussion started by: refuser
8 Replies

5. UNIX for Dummies Questions & Answers

Parameter Expansion with regular expression

Hello experts, I am exploring parameter expansion, and trying to cut the fields in a URL. Following is the requirement: I have // abc.nnt /dir1/dir2/dir3/dir4/somefile.java What i need to get is the path after dir3, and dir3 will be passed. output that i need is... (1 Reply)
Discussion started by: gjarms
1 Replies

6. Shell Programming and Scripting

Bash Parameter Expansion

I have made the following examples that print various parameter expansions text: iv-hhz-sac/hpac/hhz.d/iv.hpac..hhz.d.2016.250.070018.sac (text%.*): iv-hhz-sac/hpac/hhz.d/iv.hpac..hhz.d.2016.250.070018 (text%%.*): iv-hhz-sac/hpac/hhz (text#*.): d/iv.hpac..hhz.d.2016.250.070018.sac... (2 Replies)
Discussion started by: kristinu
2 Replies

7. Shell Programming and Scripting

Bash Parameter Expansion

#!/bin/bash SNMPW='/usr/bin/snmpwalk' while read h i do loc=$($SNMPW -v3 -u 'Myusername' -l authPriv -a SHA -A 'Password1' -x AES -X 'Password2' $i sysLocation.0 2>/dev/null) loc=${loc:-" is not snmpable."} loc=${loc##*: } loc=${loc//,/} echo "$i,$h,$loc" done < $1 My question is ... ... (1 Reply)
Discussion started by: sumguy
1 Replies

8. Shell Programming and Scripting

Bash : More parameter expansion and IFS

I am trying to become more fluent with the interworking of bash and minimize the number of external calls. Sample Data. This will be the response of the snmp query. SNMPv2-MIB::sysName.0 = STRING: SomeHostName SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.9.1.1745... (5 Replies)
Discussion started by: sumguy
5 Replies

9. Shell Programming and Scripting

Bash : Parameter expansion ${var:-file*}

Example data $ ls *somehost* 10.10.10.10_somehost1.xyz.com.log 11.11.11.11_somehost2.xyz.com.log #!/bin/bash #FILES="*.log" FILES=${FILES:-*.log} for x in $FILES do ip="${x%%_*}" # isolate IP address x="${x##*_}" # isolate hostname hnam="${x%.*}" # Remove the ".log"... (2 Replies)
Discussion started by: popeye
2 Replies

10. Shell Programming and Scripting

Use parameter expansion over a parameter expansion in bash.

Hello All, Could you please do help me here as I would like to perform parameter expansion in shell over a parameter expansion. Let's say I have following variable. path="/var/talend/nat/cdc" Now to get only nat I could do following. path1="${path%/*}" path1="${path1##*/}" Here... (8 Replies)
Discussion started by: RavinderSingh13
8 Replies
SLEEP(1)						    BSD General Commands Manual 						  SLEEP(1)

NAME
sleep -- suspend execution for an interval of time SYNOPSIS
sleep seconds DESCRIPTION
The sleep command suspends execution for a minimum of seconds. If the sleep command receives a signal, it takes the standard action. IMPLEMENTATION NOTES
The SIGALRM signal is not handled specially by this implementation. The sleep command will accept and honor a non-integer number of specified seconds (with a '.' character as a decimal point). This is a non- portable extension, and its use will nearly guarantee that a shell script will not execute properly on another system. EXIT STATUS
The sleep utility exits 0 on success, and >0 if an error occurs. EXAMPLES
To schedule the execution of a command for x number seconds later (with csh(1)): (sleep 1800; sh command_file >& errors)& This incantation would wait a half hour before running the script command_file. (See the at(1) utility.) To reiteratively run a command (with the csh(1)): while (1) if (! -r zzz.rawdata) then sleep 300 else foreach i (`ls *.rawdata`) sleep 70 awk -f collapse_data $i >> results end break endif end The scenario for a script such as this might be: a program currently running is taking longer than expected to process a series of files, and it would be nice to have another program start processing the files created by the first program as soon as it is finished (when zzz.rawdata is created). The script checks every five minutes for the file zzz.rawdata, when the file is found, then another portion processing is done courteously by sleeping for 70 seconds in between each awk job. SEE ALSO
nanosleep(2), sleep(3) STANDARDS
The sleep command is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible. HISTORY
A sleep command appeared in Version 4 AT&T UNIX. BSD
April 18, 1994 BSD
All times are GMT -4. The time now is 01:35 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy