My code is:
nb_lignes=`wc -l $1 | cut -d " " -f1`
for i in $(seq $(($nb_lignes - 1)) )
do
machine=`head $1 -n $i | tail -1`
machine1=`head $1 -n $nb_lignes | tail -1`
ssh root#$machine -x " scp /home/file.txt root#$machine1:/home && rm -r /home/file.txt"
done
Is $machine1 taken as a variable or a string? If a string, how can I change it — by adding a quote?
$machine will expand to head $1 -n $i | tail -1 result, $machine1 will expand to head $1 -n $nb_lignes | tail -1 result.
You could figured it out by yourself.
Btw, ssh root# …
$machine1 will be expanded to give the value of variable machine1, because you are using double quotes". If you had used single quotes ' then it would not have been expanded.
One possible confusion is when you embed a variable inside other text. In this case you are fine, because the trailing character is a : (root#$machine1:/home) which is not a valid character in a Bash variable name. Some shells (csh) would not have liked that, if you are not sure then you can delimit the variable name using { }, for example:
root#${machine1}:/home
Related
My current code:
while read -r rbv_line || [[ -n "$rbv_line" ]]; do
if [[ "${rbv_line}" =~ ${rbv_reg} ]]; then
rbv_downcase="${BASH_REMATCH[0],,}" &&
ruby_version="${rbv_downcase//[^0-9a-z\.\-]/}" &&
((reg_matches="${reg_matches}"+1))
printf "\n"
printf "Setting Ruby version: %s\n" "${ruby_version}"
break
fi
done < "${1}"
It does what I want. But I would love to know if I can simplify this code even more, hoping someone can help me understand the syntax.
If you see these two lines:
rbv_downcase="${BASH_REMATCH[0],,}" &&
ruby_version="${rbv_downcase//[^0-9a-z\.\-]/}" &&
Initially I tried to combine those into one using something like this:
ruby_version="${BASH_REMATCH[0],,//[^0-9a-z\.\-]/}"
That does not work.
Is there a way to combine those two parameter expansions (,, and the //[^0-9a-z\.\-]/) or is passing it through an intermediary variable the right approach?
You can view the latest version of the code here:
https://github.com/octopusnz/scripts
You cannot combine multiple parameter expansions, but...
... you can simplify this code!
The biggest gain is by using already available tools.
Instead of looping, let's use grep. It's supposed to do something when RegEx pattern is occurred, so:
grep -E "$rbv_reg" "$1" # -E is for extended RegEx
I guess your pattern isn't case sensitive, so let's disable it with -i flag.
The loop breaks after match, so let's pass -m 1 to stop processing file after first match.
You want to convert uppercase to lowercase, so let's pipe it through tr:
grep -m 1 -E -i "$rbv_reg" "$1" | tr '[:upper:]' '[:lower:]'
You then replace some characters with //[^0-9a-z\.\-]/, piping it to sed will do the trick:
grep -m 1 -E -i "$rbv_reg" "$1" | tr '[:upper:]' '[:lower:]' | sed 's/[^0-9a-z\.\-]//g'
And at the very end, let's grab the output to variable:
ruby_version="$( grep -m 1 -E -i '$rbv_reg' '$1' | tr '[:upper:]' '[:lower:]' | sed 's/[^0-9a-z\.\-]//g' )"
Since you are printing new line anyway, let's use simple echo instead of printf
All what's left is if [ -n "$ruby_version" ] to increment reg_matches
At the end, we got:
ruby_version="$(
grep -m 1 -E -i '$rbv_reg' '$1' |
tr '[:upper:]' '[:lower:]' |
sed 's/[^0-9a-z\.\-]//g'
)"
if [ -n "$ruby_version" ]; then
reg_matches="$((reg_matches+1))"
echo
echo "Setting Ruby version: $ruby_version"
fi
The advantage of above code is the fact it isn't really Bash dependent and should work in any POSIX Bourne compatible shell.
Below is the piece of code of my bash script, I want to get duplicate output of that script.
This is how my script runs
#bash check_script -a used_memory
Output is: used_memory: 812632
Desired Output: used_memory: 812632 | used_memory: 812632
get_vals() {
metrics=`command -h $hostname -p $port -a $pass info | grep -w $opt_var | cut -d ':' -f2 > ${filename}`
}
output() {
get_vals
if [ -s ${filename} ];
then
val1=`cat ${filename}`
echo "$opt_var: $val1"
# rm $filename;
exit $ST_OK;
else
echo "Parameter not found"
exit $ST_UK
fi
}
But when i used echo "$opt_var: $val1 | $opt_var: $val1" the output become: | used_memory: 812632
$opt_var is an argument.
I had a similar problem when capturing results from cat with Windows-formatted text files. One way to circumvent this issue is to pipe your result to dos2unix, e.g.:
val1=`cat ${filename} | dos2unix`
Also, if you want to duplicate lines, you can use sed:
sed 's/^\(.*\)$/\1 | \1/'
Then pipe it to your echo command:
echo "$opt_var: $val1" | sed 's/^\(.*\)$/\1 | \1/'
The sed expression works like that:
's/<before>/<after>/' means that you want to substitute <before> with <after>
on the <before> side: ^.*$ is a regular expression meaning you get the entire line, ^\(.*\)$ is basically the same regex but you get the entire line and you capture everything (capturing is performed inside the \(\) expression)
on the <after> side: \1 | \1 means you write the 1st captured expression (\1), then the space character, then the pipe character, then the space character and then the 1st captured expression again
So it captures your entire line and duplicates it with a "|" separator in the middle.
I have file with a few lines:
x 1
y 2
z 3 t
I need to pass each line as paramater to some program:
$ program "x 1" "y 2" "z 3 t"
I know how to do it with two commands:
$ readarray -t a < file
$ program "${a[#]}"
How can i do it with one command? Something like that:
$ program ??? file ???
The (default) options of your readarray command indicate that your file items are separated by newlines.
So in order to achieve what you want in one command, you can take advantage of the special IFS variable to use word splitting w.r.t. newlines (see e.g. this doc) and call your program with a non-quoted command substitution:
IFS=$'\n'; program $(cat file)
As suggested by #CharlesDuffy:
you may want to disable globbing by running beforehand set -f, and if you want to keep these modifications local, you can enclose the whole in a subshell:
( set -f; IFS=$'\n'; program $(cat file) )
to avoid the performance penalty of the parens and of the /bin/cat process, you can write instead:
( set -f; IFS=$'\n'; exec program $(<file) )
where $(<file) is a Bash equivalent to to $(cat file) (faster as it doesn't require forking /bin/cat), and exec consumes the subshell created by the parens.
However, note that the exec trick won't work and should be removed if program is not a real program in the PATH (that is, you'll get exec: program: not found if program is just a function defined in your script).
Passing a set of params should be more organized :
In this example case I'm looking for a file containing chk_disk_issue=something etc.. so I set the values by reading a config file which I pass in as a param.
# -- read specific variables from the config file (if found) --
if [ -f "${file}" ] ;then
while IFS= read -r line ;do
if ! [[ $line = *"#"* ]]; then
var="$(echo $line | cut -d'=' -f1)"
case "$var" in
chk_disk_issue)
chk_disk_issue="$(echo $line | tr -d '[:space:]' | cut -d'=' -f2 | sed 's/[^0-9]*//g')"
;;
chk_mem_issue)
chk_mem_issue="$(echo $line | tr -d '[:space:]' | cut -d'=' -f2 | sed 's/[^0-9]*//g')"
;;
chk_cpu_issue)
chk_cpu_issue="$(echo $line | tr -d '[:space:]' | cut -d'=' -f2 | sed 's/[^0-9]*//g')"
;;
esac
fi
done < "${file}"
fi
if these are not params then find a way for your script to read them as data inside of the script and pass in the file name.
I have below for loop in shell script
#!/bin/bash
#Get the year
curr_year=$(date +"%Y")
FILE_NAME=/test/codebase/wt.properties
key=wt.cache.master.slaveHosts=
prop_value=""
getproperty(){
prop_key=$1
prop_value=`cat ${FILE_NAME} | grep ${prop_key} | cut -d'=' -f2`
}
#echo ${prop_value}
getproperty ${key}
#echo "Key = ${key}; Value="${prop_value}
arr=( $prop_value )
for i in "${arr[#]}"; do
echo $i | head -n1 | cut -d "." -f1
done
The output I am getting is as below.
test1
test2
test3
I want to process the test2 from above results to below script in place of 'ABCD'
grep test12345 /home/ptc/storage/**'ABCD'**/apache/$curr_year/logs/access.log* | grep GET > /tmp/test.access.txt
I tried all the options but could not able to succeed as I am new to shell scripting.
Ignoring the many bugs elsewhere and focusing on the one piece of code you say you want to change:
for i in "${arr[#]}"; do
val=$(echo "$i" | head -n1 | cut -d "." -f1)
grep test12345 /dev/null "/home/ptc/storage/$val/apache/$curr_year/logs/access.log"* \
| grep GET
done > /tmp/test.access.txt
Notes:
Always quote your expansions. "$i", "/path/with/$val/"*, etc. (The * should not be quoted on the assumption that you want it to be expanded).
for i in $prop_value would have the exact same (buggy) behavior; using arr buys you nothing. If you want using arr to increase correctness, populate it correctly: read -r -a arr <<<"$prop_value"
The redirection is moved outside the loop -- that way the second iteration through the loop doesn't overwrite the file written by the first one.
The extra /dev/null passed to grep ensures that its behavior is consistent regardless of the number of matches; otherwise, it would display filenames only if more than one matching log file existed, and not otherwise.
In a shell script I would like to replace all underscore characters with a blank space in a function that use tr but a receive an error because I don't know of to pass a space in a variable to tr
function sanitizeDirName() {
local name=$1
local f=$2
local r=$3
echo ${name##*/} | grep -E -o $re | tr $f $r
}
sanitizeDirName "~/test_1" "_" " "
Thank you
You need to quote your variables, since they are populated from user input and could have whitespaces or metacharacters (as tripleee pointed out in the comments):
echo ${name##*/} | grep -E -o "$re" | tr "$f" "$r"
If you want to remove _ then you might want to use the -d flag
echo ${name##*/} | grep -E -o $re | tr -d $f