A bash variable contents are command line arguments, like this:
args="file-1.txt file-2.txt -k file-3.txt -k --some-argument-1 --some-argument-2"
the string -k can appear anywhere in the above string, there are some other arguments that are not -k.
Is it possible to extract all the strings (i.e. file names with all other arguments) except -k from the argument, and assign it to a bash variable?
Using sed
Is is possible to extract all the strings (i.e. file names with all other arguments) except -k from the argument, and assign it to a bash variable?
I am taking that to mean that you want to remove -k while keeping everything else. If that is the case:
$ new=$(echo " $args " | sed -e 's/[[:space:]]-k[[:space:]]/ /g')
$ echo $new
file-1.txt file-2.txt file-3.txt --some-argument-1 --some-argument-2
Using only bash
This question is tagged with bash. Under bash, the use of sed is unnecessary:
$ new=" $args "
$ new=${new// -k / }
$ echo $new
file-1.txt file-2.txt file-3.txt --some-argument-1 --some-argument-2
Piping it to sed should work:
echo $args | sed -e 's/[[:space:]]\-[[:alnum:]\-]*//g'
file-1.txt file-2.txt file-3.txt
and you can assign it to a variable with:
newvar=`echo $args | sed -e 's/[[:space:]]\-[[:alnum:]\-]*//g'`
Command-line arguments in bash should be stored in an array, to allow for arguments that contain characters that need to be quoted.
args=(file-1.txt file-2.txt -k file-3.txt -k --some-argument-1 --some-argument-2)
To extract strings other than -k, just use a for loop to filter them.
newargs=()
for arg in "${args[#]}"; do
[[ $arg = "-k" ]] && newargs+=("$arg")
done
Related
Here is a sample bash script:
#!/bin/bash
array[0]="google.com"
array[1]="yahoo.com"
array[2]="bing.com"
pasteCommand="/usr/bin/paste -d'|'"
for val in "${array[#]}"; do
pasteCommand="${pasteCommand} <(echo \$(/usr/bin/dig -t A +short $val)) "
done
output=`$pasteCommand`
echo "$output"
Somehow it shows an error:
/usr/bin/paste: invalid option -- 't'
Try '/usr/bin/paste --help' for more information.
How can I fix it so that it works fine?
//EDIT:
Expected output is to get result from the 3 dig executions in a string delimited with | character. Mainly I am using paste that way because it allows to run the 3 dig commands in parallel and I can separate output using a delimiter so then I can easily parse it and still know the dig output to which domain (e.g google.com for first result) is assigned.
First, you should read BashFAQ/050 to understand why your approach failed. In short, do not put complex commands inside variables.
A simple bash script to give intended output could be something like that:
#!/bin/bash
sites=(google.com yahoo.com bing.com)
iplist=
for site in "${sites[#]}"; do
# Capture command's output into ips variable
ips=$(/usr/bin/dig -t A +short "$site")
# Prepend a '|' character, replace each newline character in ips variable
# with a space character and append the resulting string to the iplist variable
iplist+=\|${ips//$'\n'/' '}
done
iplist=${iplist:1} # Remove the leading '|' character
echo "$iplist"
outputs
172.217.18.14|98.137.246.7 72.30.35.9 98.138.219.231 98.137.246.8 72.30.35.10 98.138.219.232|13.107.21.200 204.79.197.200
It's easier to ask a question when you specify input and desired output in your question, then specify your try and why doesn't it work.
What i want is https://i.postimg.cc/13dsXvg7/required.png
$ array=("google.com" "yahoo.com" "bing.com")
$ printf "%s\n" "${array[#]}" | xargs -n1 sh -c '/usr/bin/dig -t A +short "$1" | paste -sd" "' _ | paste -sd '|'
172.217.16.14|72.30.35.9 98.138.219.231 98.137.246.7 98.137.246.8 72.30.35.10 98.138.219.232|204.79.197.200 13.107.21.200
I might try a recursive function like the following instead.
array=(google.com yahoo.com bing.com)
paster () {
dn=$1
shift
if [ "$#" -eq 0 ]; then
dig -t A +short "$dn"
else
paster "$#" | paste -d "|" <(dig -t A +short "$dn") -
fi
}
output=$(paster "${array[#]}")
echo "$output"
Now finally clear with expected output:
domains_arr=("google.com" "yahoo.com" "bing.com")
out_arr=()
for domain in "${domains_arr[#]}"
do
mapfile -t ips < <(dig -tA +short "$domain")
IFS=' '
# Join the ips array into a string with space as delimiter
# and add it to the out_arr
out_arr+=("${ips[*]}")
done
IFS='|'
# Join the out_arr array into a string with | as delimiter
echo "${out_arr[*]}"
If the array is big (and not just 3 sites) you may benefit from parallelization:
array=("google.com" "yahoo.com" "bing.com")
parallel -k 'echo $(/usr/bin/dig -t A +short {})' ::: "${array[#]}" |
paste -sd '|'
I need to substitute a unique string in a json file: {FILES} by a bash variable that contains thousands of paths: ${FILES}
sed -i "s|{FILES}|$FILES|" ./myFile.json
What would be the most elegant way to achieve that ? The content of ${FILES} is a result of an "aws s3" command. The content would look like :
FILES="/file1.ipk, /file2.ipk, /subfolder1/file3.ipk, /subfolder2/file4.ipk, ..."
I can't think of a solution where xargs would help me.
The safest way is probably to let Bash itself expand the variable. You can create a Bash script containing a here document with the full contents of myFile.json, with the placeholder {FILES} replaced by a reference to the variable $FILES (not the contents itself). Execution of this script would generate the output you seek.
For example, if myFile.json would contain:
{foo: 1, bar: "{FILES}"}
then the script should be:
#!/bin/bash
cat << EOF
{foo: 1, bar: "$FILES"}
EOF
You can generate the script with a single sed command:
sed -e '1i#!/bin/bash\ncat << EOF' -e 's/\$/\\$/g;s/{FILES}/$FILES/' -e '$aEOF' myFile.json
Notice sed is doing two replacements; the first one (s/\$/\\$/g) to escape any dollar signs that might occur within the JSON data (replace every $ by \$). The second replaces {FILES} by $FILES; the literal text $FILES, not the contents of the variable.
Now we can combine everything into a single Bash one-liner that generates the script and immediately executes it by piping it to Bash:
sed -e '1i#!/bin/bash\ncat << EOF' -e 's/\$/\\$/g;s/{FILES}/$FILES/' -e '$aEOF' myFile.json | /bin/bash
Or even better, execute the script without spawning a subshell (useful if $FILES is set without export):
sed -e '1i#!/bin/bash\ncat << EOF' -e 's/\$/\\$/g;s/{FILES}/$FILES/' -e '$aEOF' myFile.json | source /dev/stdin
Output:
{foo: 1, bar: "/file1.ipk, /file2.ipk, /subfolder1/file3.ipk, /subfolder2/file4.ipk, ..."}
Maybe perl would have fewer limitations?
perl -pi -e "s#{FILES}#${FILES}#" ./myFile.json
It's a little gross, but you can do it all within shell...
while read l
do
if ! echo "$l" | grep -q '{DATA}'
then
echo "$l"
else
echo "$l" | sed 's/{DATA}.*$//'
echo "$FILES"
echo "$l" | sed 's/^.*{DATA}//'
fi
done <./myfile.json >newfile.json
#mv newfile.json myfile.json
Obviously I'd leave the final line commented until you were confident it worked...
Maybe just don't do it? Can you just :
echo "var f = " > myFile2.json
echo $FILES >> myFile2.json
And reference myFile2.json from within your other json file? (You should put the global f variable into a namespace if this works for you.)
Instead of putting all those variables in an environment variable, put them in a file. Then read that file in perl:
foo.pl:
open X, "$ARGV[0]" or die "couldn't open";
shift;
$foo = <X>;
while (<>) {
s/world/$foo/;
print;
}
Command to run:
aws s3 ... >/tmp/myfile.$$
perl foo.pl /tmp/myfile.$$ <myFile.json >newFile.json
Hopefully that will bypass the limitations of the environment variable space and the argument length by pulling all the processing within perl itself.
I tried to do it with function:
filter-root () {
echo $1 | perl -pe 's/ /\n/g' | perl -pe 's/.*(emacs|libreoffice|autokey|bkubuntu).*//' | perl -pe 's/^\n//'
}
but it doesn't work:
$ myList=`git ls-files`
$ filter-root myList
myList
You write bash variables alone when you assign a value to them:
MYLIST=`ls *.txt` # Remember to avoid blanks aroud the "="
but if you want bash to expand them, you have to add a $ in front of them:
echo $MYLIST # Usually is "safer" to wrap the variable with quotes - echo "$MYLIST"
You need to prepend a $ to pass the variable:
filter-root $myList
Also you should pass as "$myList" to prevent that the contents of myList is split into token by Bash ... or you could use echo "$*"
my question seems to be general, but i can't find any answers.
In sed command, how can you replace the substitution pattern by a value returned by a simple bash function.
For instance, I created the following function :
function parseDates(){
#Some process here with $1 (the pattern found)
return "dateParsed;
}
and the folowing sed command :
myCatFile=`sed -e "s/[0-3][0-9]\/[0-1][0-9]\/[0-9][0-9]/& parseDates &\}/p" myfile`
I found that the caracter '&' represents the current pattern found, i'd like it to be passed to my bash function and the whole pattern to be substituted by the pattern found +dateParsed.
Does anybody have an idea ?
Thanks
you can use the "e" option in sed command like this:
cat t.sh
myecho() {
echo ">>hello,$1<<"
}
export -f myecho
sed -e "s/.*/myecho &/e" <<END
ni
END
you can see the result without "e":
cat t.sh
myecho() {
echo ">>hello,$1<<"
}
export -f myecho
sed -e "s/.*/myecho &/" <<END
ni
END
Agree with Glenn Jackman.
If you want to use bash function in sed, something like this :
sed -rn 's/^([[:digit:].]+)/`date -d #&`/p' file |
while read -r line; do
eval echo "$line"
done
My file here begins with a unix timestamp (e.g. 1362407133.936).
Bash function inside sed (maybe for other purposes):
multi_stdin(){ #Makes function accepet variable or stdin (via pipe)
[[ -n "$1" ]] && echo "$*" || cat -
}
sans_accent(){
multi_stdin "$#" | sed '
y/àáâãäåèéêëìíîïòóôõöùúûü/aaaaaaeeeeiiiiooooouuuu/
y/ÀÁÂÃÄÅÈÉÊËÌÍÎÏÒÓÔÕÖÙÚÛÜ/AAAAAAEEEEIIIIOOOOOUUUU/
y/çÇñÑߢÐð£Øø§µÝý¥¹²³ªº/cCnNBcDdLOoSuYyY123ao/
'
}
eval $(echo "Rogério Madureira" | sed -n 's#.*#echo & | sans_accent#p')
or
eval $(echo "Rogério Madureira" | sed -n 's#.*#sans_accent &#p')
Rogerio
And if you need to keep the output into a variable:
VAR=$( eval $(echo "Rogério Madureira" | sed -n 's#.*#echo & | desacentua#p') )
echo "$VAR"
do it step by step. (also you could use an alternate delimiter , such as "|" instead of "/"
function parseDates(){
#Some process here with $1 (the pattern found)
return "dateParsed;
}
value=$(parseDates)
sed -n "s|[0-3][0-9]/[0-1][0-9]/[0-9][0-9]|& $value &|p" myfile
Note the use of double quotes instead of single quotes, so that $value can be interpolated
I'd like to know if there's a way to do this too. However, for this particular problem you don't need it. If you surround the different components of the date with ()s, you can back reference them with \1 \2 etc and reformat however you want.
For instance, let's reverse 03/04/1973:
echo 03/04/1973 | sed -e 's/\([0-9][0-9]\)\/\([0-9][0-9]\)\/\([0-9][0-9][0-9][0-9]\)/\3\/\2\/\1/g'
sed -e 's#[0-3][0-9]/[0-1][0-9]/[0-9][0-9]#& $(parseDates &)#' myfile |
while read -r line; do
eval echo "$line"
done
You can glue together a sed-command by ending a single-quoted section, and reopening it again.
sed -n 's|[0-3][0-9]/[0-1][0-9]/[0-9][0-9]|& '$(parseDates)' &|p' datefile
However, in contrast to other examples, a function in bash can't return strings, only put them out:
function parseDates(){
# Some process here with $1 (the pattern found)
echo dateParsed
}
Is it possible to do a grep with keywords stored in the array.
Here is the possible code snippet; how can I correct it?
args=("key1" "key2" "key3")
cat file_name |while read line
echo $line | grep -q -w ${args[c]}
done
At the moment, I can search for only one keyword. I would like to search for all the keywords which is stored in args array.
args=("key1" "key2" "key3")
pat=$(echo ${args[#]}|tr " " "|")
grep -Eow "$pat" file
Or with the shell
args=("key1" "key2" "key3")
while read -r line
do
for i in ${args[#]}
do
case "$line" in
*"$i"*) echo "found: $line";;
esac
done
done <"file"
You can use some bash expansion magic to prefix each element with -e and pass each element of the array as a separate pattern. This may avoid some precedence issues where your patterns may interact badly with the | operator:
$ grep ${args[#]/#/-e } file_name
The downside to this is that you cannot have any spaces in your patterns because that will split the arguments to grep. You cannot put quotes around the above expansion, otherwise you get "-e pattern" as a single argument to grep.
This is one way:
args=("key1" "key2" "key3")
keys=${args[#]/%/\\|} # result: key1\| key2\| key3\|
keys=${keys// } # result: key1\|key2\|key3\|
grep "${keys}" file_name
Edit:
Based on Pavel Shved's suggestion:
( IFS="|"; keys="${args[*]}"; keys="${keys//|/\\|}"; grep "${keys}" file_name )
The first version as a one-liner:
keys=${args[#]/%/\\|}; keys=${keys// }; grep "${keys}" file_name
Edit2:
Even better than the version using IFS:
printf -v keys "%s\\|" "${args[#]}"; grep "${keys}" file_name
I tend to use process substitution for everything. It's convenient when combined with grep's -f option:
Obtain patterns from FILE, one per line.
(Depending on the context, you might even want to combine that with -F, -x or -w, etc., for awesome effects.)
So:
#! /usr/bin/env bash
t=(8 12 24)
seq 30 | grep -f <(printf '%s\n' "${t[#]}")
and I get:
8
12
18
24
28
I basically write a pseudo-file with one item of the array per line, and then tell grep to use each of these lines as a pattern.
The command
( IFS="|" ; grep --perl-regexp "${args[*]}" ) <file_name
searches the file for each keyword in an array. It does so by constructing regular expression word1|word2|word3 that matches any word from the alternatives given (in perl mode).
If I there is a way to join array elements into a string, delimiting them with sequence of characters (namely, \|), it could be done without perl regexp.
perhaps something like this;
cat file_name |while read line
for arg in ${args[#]}
do
echo $line | grep -q -w $arg}
done
done
not tested!