You are welcome. If you try:
You'll notice that the first one evaluates to -n and the second one to -n ''
In the first case the there is no protection of variable p, which contains an empty field. Since there is not protective quotes around $p, the result is field split and since $p is empty this results in 0 fields. So wat remains "-n" which is a test if the string "-n" is non empty
([ "$somestring" ] if the same as [ -n "$somestring"], I prefer the latter for clarity, so in fact [ -n ] is equivalent to [ -n -n ])
In the second case the result of "$p" is not field split and so the -n is interpreted as an operator with one field as parameter, which contains an empty variable, and this evaluates to false .
So that is yet another reason to put quotes around variable expansions.
I hope this clarifies things...
Last edited by Scrutinizer; 06-21-2016 at 03:55 PM..
This User Gave Thanks to Scrutinizer For This Post:
Hi,
I need to delete an empty directory in a temp directory except "dir5" (keep everything that is not empty).
Plese advise.
Here is an example of my directory.
/dir/temp/
dir1 - delete if this is empty
dir2 - delete if this is empty
dir3 - delete if this is empty
dir4 - delete if this... (7 Replies)
I know this one was answered before in forum below -
https://www.unix.com/unix-dummies-questions-answers/58210-removing-empty-folders-using-find-command.html
But that one is closed & I have a question so here it goes.
I want to delete all 2006 files. Now if along with the files, if the... (2 Replies)
Hello:
I searched here for "vi -c" but found no hits.
How can I use vi -c to remove ALL empty lines, regardless of how many?
I tried
<code>
vi -c ":g/^$/d | wq" filename
</code>
but I have to run it several times.
This is NOT homework. :)
Thanks for your time. (3 Replies)
Hi all,
I'm trying to remove when this condition is met: an empty and the next one
I'm using this command:
sed '/^$/N; s/&//' file
Which searches for an empty line, N attaches it to the next line, and substituing the combination with nothing.... but it is not working.
What I'm missing... (1 Reply)
Hi all !
I'm sure it is a basic question but I didn't find any threads that fit my need.
How to remove empty fields with awk?
Or in other words, how to shift all the fields after an empty field on the left?
input:
1|2||3|4|5||6
wanted:
1|2|3|4|5|6
I tried:
awk '{for(i=1; i<=NF;... (7 Replies)
Hello:
Is there a simple way to remove empty records of FASTA format file?
A FASTA format consists of two parts: header and sequence (for non-biologist, Wiki for details of course!). The header always start with ">" for the name of the sequence. The header must be in this ONLY single line.... (9 Replies)
Hello,
I need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line... An example of entries in the file would be:
SRVXPAPI001 ERRO JUN24 07:28:34 1775
REASON= 0000, PROCID= #E506 #1065: TPCIPPR, INDEX= 003F
... (8 Replies)
Hi all,
I've got a file that has 12 fields. I've merged 2 files and there will be some duplicates in the following:
FILE:
1. ABC, 12345, TEST1, BILLING, GV, 20/10/2012, C, 8, 100, AA, TT, 100
2. ABC, 12345, TEST1, BILLING, GV, 20/10/2012, C, 8, 100, AA, TT, (EMPTY)
3. CDC, 54321, TEST3,... (4 Replies)
Discussion started by: tugar
4 Replies
LEARN ABOUT DEBIAN
cvm-checkpassword
cvm-checkpassword(8) System Manager's Manual cvm-checkpassword(8)NAME
cvm-checkpassword - checkpassword interface for CVM modules
SYNOPSIS
cvm-checkpassword CVM Command [ arguments ... ]
DESCRIPTION
http://cr.yp.to/checkpwd/interface.html
http://untroubled.org/cvm/cvm.html
See the above links for details on both the CVM and checkpassword interfaces. To use this interface with qmail-pop3d(8), use the following
command line:
/var/qmail/bin/qmail-popup
cvm-checkpassword cvm-unix
/var/qmail/bin/qmail-pop3d ./Maildir/
Note: The default mode of operations for this module is to attempt to split a domain name from the account name. If this is not desirable,
set $CVM_ACCOUNT_SPLIT_CHARS to an empty string.
SEE ALSO cvm-pwfile(8), cvm-qmail(8), cvm-unix(8), cvm-sql(8), cvm-vmailmgr(8), cvm-benchclient(8), cvm-testclient(8)
http://untroubled.org/cvm/cvm.html
cvm-checkpassword(8)