Sponsored Content
Full Discussion: need help understanding mv
Top Forums Shell Programming and Scripting need help understanding mv Post 302357037 by cfajohnson on Monday 28th of September 2009 01:05:44 PM
Old 09-28-2009
Quote:
Originally Posted by methyl
To cfajohnson. I did not expect this response from you who I recognise as an expert in shell syntax. The O/P script did not contain the problem, my initial response did not contain the problem, but the example was designed to teach.

Please explain the error message in my example in your own words.

I was not commenting on any error message. I was answering the question, "Can you briefly explain the curly brackets."

My comment was about this:

Code:
mv "${file1}" "${file1}.TMP"
mv "${file2}" "${file2}.TMP"

The braces are not necessary in that example. They are not wrong, but they do nothing.

If the example had been:

Code:
mv "${file1}" "${file1}_TMP"
mv "${file2}" "${file2}_TMP"

...then they would have been necessary but only in the second instance on each line.
 

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Need help for understanding of script

# sub: find block (in cols), return line-numbers (begin-end) or 0 if notfound sub findb{ my ($exp1,$col1,$exp2,$col2)= @_; # $exp = expression to find, $col - column to search in my $cnt=0; my ($val1,$val2); my ($beg,$end); for($cnt=1;$cnt<=65536;$cnt++){ $val1 =... (3 Replies)
Discussion started by: suvenduperl
3 Replies

2. UNIX for Dummies Questions & Answers

understanding {%/*}/

Hi Gurus: I am trying to understand the following line of code.I did enough of googling to understand but no luck.Please help me understand the follow chunk of code: X=$0 MOD=${X%/*}/env.ksh X is the current script from which I am trying to execute. Say if X=test.ksh $MOD is echoing :... (3 Replies)
Discussion started by: vemana
3 Replies

3. Solaris

Understanding 'du' command

Hi I have a questions related 2 commands : 'du' and 'ls'. Why is the difference between output of 'du' and 'ls' cmd's ? Command 'du' : ------------------ jakubn@server1 /home/jakubn $ du -s * 4 engine.ksh 1331 scripts 'du -s *' ---> shows block count size on disk (512 Bytes... (5 Replies)
Discussion started by: presul
5 Replies

4. Shell Programming and Scripting

Understanding <<EOF

Hi all I stuck with a problem. I want to understand the execution of the below code. Can any one please help me `sqlplus username/passwd@DB << EOF set serveroutput on declare begin sql_query; end; / commit / quit EOF` My ques is why do we use EOF and how does it help. (4 Replies)
Discussion started by: parthmittal2007
4 Replies

5. Shell Programming and Scripting

Understanding a regex

Hi, Please help me to understand the bold segments in the below regex. Both are of same type whose meaning I am looking for. find . \( -iregex './\{6,10\}./src' \) -type d -maxdepth 2 Output: ./20111210.0/src In continuation to above: sed -e 's|./\(*.\{1,3\}\).*|\1|g' Output: ... (4 Replies)
Discussion started by: vibhor_agarwali
4 Replies

6. Shell Programming and Scripting

Help understanding the script

Hi Guys, I am new to scripting , I am trying to rebuild a script based on an old script. Can someone help me figure out what the script is doing? This is only a part of the script. I am looking to interpret these two points in the scripts:- 1) test=`echo $?` while I do not... (3 Replies)
Discussion started by: rajsan
3 Replies

7. Shell Programming and Scripting

Help with understanding of alias

Hi, I saw the following explanation about alias in bash from gnu website, but I didn't get the meaning: Bash always reads at least one complete line of input before executing any of the commands on that line. Aliases are expanded when a command is read, not when it is executed. Therefore, an... (3 Replies)
Discussion started by: Roy987
3 Replies

8. UNIX for Dummies Questions & Answers

Understanding lseek

I tried to use lseek system call to determine the number of bytes in a file. To do so, I used open system call with O_APPEND flag to open a file. As lseek returns the current offset so I called lseek for opened file with offset as zero and whence as SEEK_CUR. So I guess it must return the number of... (3 Replies)
Discussion started by: Deepak Raj
3 Replies

9. Shell Programming and Scripting

Need your help in understanding this

Hi, I found this in a script and I would like to know how this works Code is here: # var1=PART1_PART2 # var2=${var1##*_} # echo $var2 PART2 I'm wondering how ##* makes the Shell to understand to pick up the last value from the given. (2 Replies)
Discussion started by: sathyaonnuix
2 Replies
COMBINE(1)																COMBINE(1)

NAME
combine - combine sets of lines from two files using boolean operations SYNOPSIS
combine file1 and file2 combine file1 not file2 combine file1 or file2 combine file1 xor file2 _ file1 and file2 _ _ file1 not file2 _ _ file1 or file2 _ _ file1 xor file2 _ DESCRIPTION
combine combines the lines in two files. Depending on the boolean operation specified, the contents will be combined in different ways: and Outputs lines that are in file1 if they are also present in file2. not Outputs lines that are in file1 but not in file2. or Outputs lines that are in file1 or file2. xor Outputs lines that are in either file1 or file2, but not in both files. "-" can be specified for either file to read stdin for that file. The input files need not be sorted, and the lines are output in the order they occur in file1 (followed by the order they occur in file2 for the two "or" operations). Bear in mind that this means that the operations are not commutative; "a and b" will not necessarily be the same as "b and a". To obtain commutative behavior sort and uniq the result. Note that this program can be installed as "_" to allow for the syntactic sugar shown in the latter half of the synopsis (similar to the test/[ command). It is not currently installed as "_" by default, but you can alias it to that if you like. SEE ALSO
join(1) AUTHOR
Copyright 2006 by Joey Hess <joey@kitenet.net> Licensed under the GNU GPL. moreutils 2012-04-09 COMBINE(1)
All times are GMT -4. The time now is 02:27 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy