Well... It's a cluster. The person who wrote it seems to me to be insane.
Code:
cat /etc/passwd | grep "^[^:][^:][^:][^:]:"
This greps for lines beginning with "XXXX:", where X is any character except a colon. So basically, this will only show you 4-letter users. ... Kinda weird, but.. okay. Also, the person that wrote it is perpetuating the misunderstanding that cat serves a function for single files. (Grep can take files as arguments.)
Code:
| sed '1,$s/^\([^:]*\):[^:]*:\([^:]*\):.*$/ \1 \2 /'
That is the most ridiculous thing I've ever seen. Unless I'm missing something big, the purpose of it is apparently to pull out only the username and the uid. It could have been accomplished so much more simply, clearly, and efficiently by replacing it with a cut command (this is what cut was made for!) like this:
Code:
| cut -d: -f1,3 --output-delimiter=' '
Lastly...
Code:
| sort -nrk3 -t:
What I think this is trying to do: sort the 4-letter users in descending order of their uid (so bob with uid 1100 would be before aaron with uid 505). However, the code is broken, probably because the person's over-complicated sed string is broken. To fix it, just change that trailing colon to a quoted space character:
Code:
' '
Look up those options in the sort man page if you're curious.
Long story short, here's what the command should be:
Hi I am new to shell script programming...
want to know the process of the following:
if
then
echo "$0: missing argument for option(s) :$MISSINGOPTARG"
echo "usage" $USAGE"
exit 1
fi (1 Reply)
how does below tr command replace nonletters with newlines?
I think I understand tr -cs '\n' part.. but what is
A-Za-z\' <--- what is this??
tr -cs A-Za-z\' '\n' |
-c --complement
-s, --squeeze-repeats
replace each input sequence of a repeated character that is... (0 Replies)
Could someone give me a quick simple explanation for the AWK command.
And also help me to explain the code i have made. I have made some general comments about it myself. I was wondering if people could help me with the rest:
awk -F'' 'END {
fmt = "%-20s\t%s\t%s\n" ... (0 Replies)
Hi
I have a line/command which greps certain pattern () from the file and 22 lines AFTER that:
nawk '/\/{c=22}c&&c--' input_file
Can somebody explain the coding in this command (what " c&&c-- " does)? and how to modify this command to output 22 lines BEFORE this pattern () Thanks a lot ... (3 Replies)
I have the following piece of codes. Please explain it to me in great detail how are these codes working.
1. #include <stdio.h>
int main(){
int x;
x=0;
while (x<2 && fork()){
if (!fork()) execlp("echo","x++","x",0);
x++;
system("echo x+x");
}
}
2.
#include <stdio.h>
int i;... (1 Reply)
Its great someone provided this script that strips out a filename and extension but can someone explain how each line works?
file1='Jane Mid Doe.txt'
newfile='Jane.txt'
1) ext=${file1##*.}
2) filename=${file%%.???}
3) set -- $filename
4) newfile="1.$extension" (1 Reply)
Can you please explain the following code plz?
my_cd=' '
while getopts :e: OPTION;
do
case "$OPTION" in
e) my_cd ="$OPTARG";;
esac
done
if ; then
echo " >>> ERROR - I am wrong"
echo " >>> ERROR - Hello"
exit 99
fi
What I don't understand is what is OPTION or... (3 Replies)
Hi all,
I need your help in understanding the meaning and syntax of the below nawk line.
Here is an extract of a script which I use daily and works well. The script extracts the hostnames and messages within a syslog file. I would also like to extract the message time in the 3rd column by... (2 Replies)
1. I've been asked to provide a detailed description on how Minix's source code is organised. This may sound slightly simple, but what exactly am I to refer to when explaining? Any documents that would provide assistance to understand whats being asked? Thanks
2. Not applicable:
3.... (1 Reply)
Hi. Can somebody please explain the following lines of KSH code for me? The code checks all sub directories in a specific location which are numbered (E.g. test_01, test_02 ... etc.), then finds the one with highest number and extracts that number from the dir name into the variable num. I'd just... (9 Replies)
12-18-2011
