Hi there,
I have a very general question. I'm rather new to (bash) shell scripting and I don't understand how conditions work... I've read numerous tutorials but I don't get it. I really don't. Sometime what I do works, sometime it doesn't and that's frustating. So what's the actual difference between these three forms. I haven't so far been successful in using the last one - always get a "syntax error". As well, what are their operators ? When should you use "-eq" or "==" ?
Code:
if [ ... ] if [[ ... ]] if (( ... ))
As an example, why does the first one works but not the second!?!
Code:
if [[ -n $a ]] if [ -n $a ]
Also, how on Earth do you do stuff like (I know this doesn't work - but I've seen things alike) :
Code:
(( 2 > 1 )) && (( echo "2 > 1" ))
If you know where a nice tutorial exists on the matter, I'll be glad as well!
Many thanks
Hello,
I have the following script :
BEGIN {
print "1 ***";
split("abc",T,"");
T="e";
T="z";
T="y";
for (i in T) printf("%i:%s ",i,T); print "";
for (i=1; i<=length(T); i++) printf(T); print ""
print "2 ***";
asort(T,U);
for (i in U) printf("%i:%s ",i,U); ... (3 Replies)
this is my program i am trying to compile
/* filedata -- display information about a file */
#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
/*
* use octarray for determing
* if permission bits set
*/
static short octarray = {0400, 0200, 0100,... (2 Replies)
I'm just trying to confirm that I understand someone's code correctly.
If someone has code that says:
$foo ||= mysub();
I'm assuming that it means if $foo is nothing or undef, then assign it some value via mysub(). If I'm wrong on this, please let me know.
Also, what's the difference... (4 Replies)
I have a text file called file1 which contains the text: "ls -l"
When I enter this command:
bash < file1 > file1
file1 gets erased. However if I enter this command:
bash < file1 > newfile
the output from "ls -l" is stored in newfile. My question is why doesn't file1's text ("ls -l") get... (3 Replies)
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
1)find all lines in file ,myf that contain all the words cat dog and mouse in any order and start with the letter... (1 Reply)
I learn using RS in awk to extract portion of file in this forum which is wonderful solution to the problem. However, I don't understand how exactly it operates.
I don't quite understand the mechanism behind how searching for /DATA2/ can result in extracting the whole section under "DATA2"
... (3 Replies)
Hi all.
The startup script in /usr/local/bin.
After user login the script run an application.
Iwould in the same way run the another application.
How to make It similar?
Where I must to look?
Regards. (3 Replies)
if {"$my_ext_type" = MAIN]; then
cd $v_sc_dir
Filex.SH $v_so_dir\/$v_fr_file
Can somebody tell me what does this suggest. I am pretty new to unix and
I am getting confused.
What i understood from here is
If we have a file extension name as MAIN
which we have then we change the directory to... (1 Reply)
I don't understand conditions :(