I'm looking to automate dns-add by creating two for loop variables. I'm not sure how this is possible. I know my code below is wrong. I'm having difficulties understanding how to create two variables in a one-liner.
for i in `cat list.csv`;
for g in `cat list2.csv`; do
echo $i;
echo $g;
dns-add-record --zone=impl.wd2.wd --record=$i --type=CNAME --record-value=$g
done;
done
The only thing i thought might work was this, but I doubt it'll work. Does anyone have any hints?
for i in `cat list.csv` && \
for g in `cat list2.csv ; do
echo $i && $g;
dns-add-record --zone=impl.wd2.wd --record=$i --type=CNAME --record-value=$g
done;
done
A for loop is the wrong construct for iterating over any file (see Bash FAQ 001), let alone two files. Use a while loop with the read command instead.
while read -u 3 i; read -u 4 g; do
echo "$i"
echo "$g"
dns-add-record --zone=impl.wd2.wd --record="$i" --type=CNAME --record-value="$g"
done 3< list.csv 4< list2.csv
I think you are missing one do ?
for i in `cat list.csv`; **do**
for g in `cat list2.csv`; do
echo $i;
echo $g;
dns-add-record --zone=impl.wd2.wd --record=$i --type=CNAME --record- value=$g
done; done
Related
I want to create a Linux command which creates a file containing 10 random numbers.
This is a solution to generate 10 random numbers;
RANDOM=$$
for i in `seq 10`
do
echo $RANDOM
done
It is working to generate random numbers but how can I combine this with 'touch' command? Should I create a loop?
Using touch? Like this?
touch file.txt && RANDOM=$$
for i in `seq 10`
do
echo $RANDOM
done >> file.txt
Not sure why you need touch though, this will also work:
for i in `seq 10`; do echo $RANDOM; done > file.txt
Use >> to write to file, $1 is first argument of your .sh file
FILE=$1
RANDOM=$$
for i in `seq 10`
do
echo $RANDOM >> $FILE
echo "\n" >> $FILE
done
You could use head(1) and od(1) or GNU gawk with random(4).
For example, perhaps
head -20c /dev/random | od -s > /tmp/tenrandomnumbers.txt
Please explain to me why the very last echo statement is blank? I expect that XCODE is incremented in the while loop to a value of 1:
#!/bin/bash
OUTPUT="name1 ip ip status" # normally output of another command with multi line output
if [ -z "$OUTPUT" ]
then
echo "Status WARN: No messages from SMcli"
exit $STATE_WARNING
else
echo "$OUTPUT"|while read NAME IP1 IP2 STATUS
do
if [ "$STATUS" != "Optimal" ]
then
echo "CRIT: $NAME - $STATUS"
echo $((++XCODE))
else
echo "OK: $NAME - $STATUS"
fi
done
fi
echo $XCODE
I've tried using the following statement instead of the ++XCODE method
XCODE=`expr $XCODE + 1`
and it too won't print outside of the while statement. I think I'm missing something about variable scope here, but the ol' man page isn't showing it to me.
Because you're piping into the while loop, a sub-shell is created to run the while loop.
Now this child process has its own copy of the environment and can't pass any
variables back to its parent (as in any unix process).
Therefore you'll need to restructure so that you're not piping into the loop.
Alternatively you could run in a function, for example, and echo the value you
want returned from the sub-process.
http://tldp.org/LDP/abs/html/subshells.html#SUBSHELL
The problem is that processes put together with a pipe are executed in subshells (and therefore have their own environment). Whatever happens within the while does not affect anything outside of the pipe.
Your specific example can be solved by rewriting the pipe to
while ... do ... done <<< "$OUTPUT"
or perhaps
while ... do ... done < <(echo "$OUTPUT")
This should work as well (because echo and while are in same subshell):
#!/bin/bash
cat /tmp/randomFile | (while read line
do
LINE="$LINE $line"
done && echo $LINE )
One more option:
#!/bin/bash
cat /some/file | while read line
do
var="abc"
echo $var | xsel -i -p # redirect stdin to the X primary selection
done
var=$(xsel -o -p) # redirect back to stdout
echo $var
EDIT:
Here, xsel is a requirement (install it).
Alternatively, you can use xclip:
xclip -i -selection clipboard
instead of
xsel -i -p
I got around this when I was making my own little du:
ls -l | sed '/total/d ; s/ */\t/g' | cut -f 5 |
( SUM=0; while read SIZE; do SUM=$(($SUM+$SIZE)); done; echo "$(($SUM/1024/1024/1024))GB" )
The point is that I make a subshell with ( ) containing my SUM variable and the while, but I pipe into the whole ( ) instead of into the while itself, which avoids the gotcha.
#!/bin/bash
OUTPUT="name1 ip ip status"
+export XCODE=0;
if [ -z "$OUTPUT" ]
----
echo "CRIT: $NAME - $STATUS"
- echo $((++XCODE))
+ export XCODE=$(( $XCODE + 1 ))
else
echo $XCODE
see if those changes help
Another option is to output the results into a file from the subshell and then read it in the parent shell. something like
#!/bin/bash
EXPORTFILE=/tmp/exportfile${RANDOM}
cat /tmp/randomFile | while read line
do
LINE="$LINE $line"
echo $LINE > $EXPORTFILE
done
LINE=$(cat $EXPORTFILE)
I am using:
inotifywait -m -q -e close_write --format %f . | while IFS= read -r file; do
cp -p "$file" /path/to/other/directory
done
to monitor a folder for file completion, then moving it to another folder.
Files are made in pairs but at separate times, ie File1_001.txt is made at 3pm, File1_002.txt is made at 9pm. I want to monitor for the completion of BOTH files, then launch a script.
script.sh File1_001.txt File1_002.txt
So I need to have another inotifywait command or a different utility, that can also identify that both files are present and completed, then start the script.
Does anyone know how to solve this problem?
I found a Linux box with inotifywait installed on it, so now I understand what it does and how it works. :)
Is this what you need?
#!/bin/bash
if [ "$1" = "-v" ]; then
Verbose=true
shift
else
Verbose=false
fi
file1="$1"
file2="$2"
$Verbose && printf 'Waiting for %s and %s.\n' "$file1" "$file2"
got1=false
got2=false
while read thisfile; do
$Verbose && printf ">> $thisfile"
case "$thisfile" in
$file1) got1=true; $Verbose && printf "... it's a match!" ;;
$file2) got2=true; $Verbose && printf "... it's a match!" ;;
esac
$Verbose && printf '\n'
if $got1 && $got2; then
$Verbose && printf 'Saw both files.\n'
break
fi
done < <(inotifywait -m -q -e close_write --format %f .)
This runs a single inotifywait but parses its output in a loop that exits when both files on the command line ($1 and $2) are seen to have been updated.
Note that if one file is closed and then later is reopened while the second file is closed, this script obviously will not detect the open file. But that may not be a concern in your use case.
Note that there are many ways of building a solution -- I've shown you only one.
Hello from a Linux Bash newbie!
I have a list.txt containing a list of files which I want to copy to a destination($2). These are unique images but some of them have the same filename.
My plan is to loop through each line in the text file, with the copy to the destination occurring when the file is not there, and a mv rename happening when it is present.
The problem I am having is creating the pathname to check the file against. In the code below, I am taking the filename only from the pathname, and I want to add that to the destination ($2) with the "/" in between to check the file against.
When I run the program below I get "Permission Denied" at line 9 which is where I try and create the path.
for line in $(cat list.txt)
do
file=$[ basename $line ]
path=$[ $2$file ]
echo $path
if [ ! -f $path ];
then
echo cp $line $2
else
echo mv $line.DUPLICATE $2
fi
done
I am new to this so appreciate I may be missing something obvious but if anyone can offer any advice it would be much appreciated!
Submitting this since OP is new in BASH scripting no good answer has been posted yet.
DESTINATION="$2"
while read -r line; do
file="${line##*/}"
path="$2/$file"
[[ ! -f $path ]] && cp "$line" "$path" || mv "$line" "$path.DUP"
done < list.txt
Don't have logic for counting duplicates at present to keep things simple. (Which means code will take care of one dup entry) As an alternative you get uniq from list.txt beforehand to avoid the duplicate situation.
#anubhava: Your script looks good. Here is a small addition to it to work with several dupes.
It adds a numer to the $path.DUP name
UniqueMove()
{
COUNT=0
while [ -f "$1" ]
do
(( COUNT++ ))
mv -n "$1" "$2$COUNT"
done
}
while read -r line; do
file="${line##*/}"
path="$2/$file"
[[ ! -f $path ]] && cp "$line" "$path" || UniqueMove "$line" "$path.DUP"
done < list.txt
I have a simple BASH command that looks like
for i in `seq 2`; do echo $i; done; > out.dat
When this runs the output of seq 2 is output to the terminal and nothing is output to the data file (out.dat)
I am expecting standard out to be redirected to out.dat like it does simply running the command seq 2 > out.dat
Remove your semicolon.
for i in `seq 2`; do echo "$i"; done > out.dat
SUGGESTIONS
Also as suggested by Fredrik Pihl, try not to use external binaries when they are not needed, or at least when practically not:
for i in {1..2}; do echo "$i"; done > out.dat
for (( i = 1; i <= 2; ++i )); do echo "$i"; done > out.dat
for i in 1 2; do echo "$i"; done > out.dat
Also, be careful of outputs in words that may cause pathname expansion.
for a in $(echo '*'); do echo "$a"; done
Would show your files instead of just a literal *.
$() is also recommended as a clearer syntax for command substitution in Bash and POSIX shells than backticks (`), and it supports nesting.
The cleaner solutions as well for reading output to variables are
while read var; do
...
done < <(do something)
And
read ... < <(do something) ## Could be done on a loop or with readarray.
for a in "${array[#]}"; do
:
done
Using printf can also be an easier alternative with respect to the intended function:
printf '%s\n' {1..2} > out.dat
Another possibility, for the sake of completeness: You can move the output inside the loop, using >> to append to the file, if it exists.
for i in `seq 2`; do echo $i >> out.dat; done;
Which one is better certainly depends on the use case. Writing the file in one go is certainly better than appending to it a thousand times. Also, if the loop contains multiple echo statements, all of which shall go to the file, doing done > out.dat is probably more readable and easier to maintain. The advantage of this solution, of course, is that it gives more flexibility.
Try:
(for i in `seq 2`; do echo $i; done;) > out.dat