NOTE FROM OP: Oops. My mistake. I happened to let grep hunt for something(s) non-existent. Of course I got no output. And yes, this is a dup of another question.
<><><><><><><><><><><><><><><><><><><><>
There are many answers on the web to (most of) this question. The "most of" part is my problem.
How do I capture the output of a command line into a bash array when the command line contains pipe chars, "|"?
array=($(ps -ef | grep myproc | grep -v grep))
doesn't work. Neither does:
array=(`ps -ef | grep myproc | grep -v grep`)
(those are backquotes in case your font mangles them).
And, can the given answer be use with array+= syntax?
array=($(ps -ef | grep myproc | grep -v grep))
works perfectly well. You can check it when you show the number of elements in your array
echo ${#array[*]}
or the complete array with
echo ${array[*]}
Related
i tried to make bash script that can find "keyword" inside *.desktop file. my approach is to set some keyword as array, then pass it to grep, it work flawlessly until the keyword has at least two word separated by space.
what it should be
cat /usr/share/applications/*.desktop | grep -i "Mail Reader"
what i have tried
search=$(printf 'Name=%s' "${appsx[$index]}")
echo \""$search\"" #debug
cat /usr/share/applications/*.desktop | grep -i $search
search=$(printf 'Name=%s' "${appsx[$index]}")
echo \""$search\"" #debug
cat /usr/share/applications/*.desktop | grep -i \""$search\""
search=$(printf '"Name=%s"' "${appsx[$index]}")
echo $search #debug
cat /usr/share/applications/*.desktop | grep -i $search
any suggestions is highly appreciated
If you simply assign Mail Reader to the variable search like below
search=Mail Reader
bash would complain that Reader command is not found as it takes anything after that first blank character to be a subsequent command. What you need is
search="Mail Reader" # 'Mail Reader' would also do.
In the case of your command substitution, things are not different, you need double quote wrappers though, as the substitution itself would not happen inside the single
quotes
search="$(command)"
In your case, you did an overkill using a command substitution though. It could be well simplified to:
search="Name=${appsx[$index]}"
# Then do the grep.
# Note that cat-grep combo could be simplified to
# -h suppresses printing filenames to get same result as cat .. | grep
grep -ih "$search" /usr/share/applications/*.desktop
I am attempting to get a list of running VirtualBox VMs (the UUIDs) and put them into an array. The command below produces the output below:
$ VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}'
f93c17ca-ab1b-4ba2-95e5-a1b0c8d70d2a
46b285c3-cabd-4fbb-92fe-c7940e0c6a3f
83f4789a-b55b-4a50-a52f-dbd929bdfe12
4d1589ba-9153-489a-947a-df3cf4f81c69
I would like to take those UUIDs and put them into an array (possibly even an associative array for later use, but a simple array for now is sufficient)
If I do the following:
array1="( $(VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}') )"
The commands
array1_len=${#array1[#]}
echo $array1_len
Outputs "1" as in there's only 1 element. If I print out the elements:
echo ${array1[*]}
I get a single line of all the UUIDs
( f93c17ca-ab1b-4ba2-95e5-a1b0c8d70d2a 46b285c3-cabd-4fbb-92fe-c7940e0c6a3f 83f4789a-b55b-4a50-a52f-dbd929bdfe12 4d1589ba-9153-489a-947a-df3cf4f81c69 )
I did some research (Bash Guide/Arrays on how to tackle this and found this with command substitution and redirection, but it produces an empty array
while read -r -d '\0'; do
array2+=("$REPLY")
done < <(VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}')
I'm obviously missing something. I've looked at several simiar questions on this site such as:
Reading output of command into array in Bash
AWK output to bash Array
Creating an Array in Bash with Quoted Entries from Command Output
Unfortunately, none have helped. I would apprecaite any assistance in figuring out how to take the output and assign it to an array.
I am running this on macOS 10.11.6 (El Captain) and BASH version 3.2.57
Since you're on a Mac:
brew install bash
Then with this bash as your shell, pipe the output to:
readarray -t array1
Of the -t option, the man page says:
-t Remove a trailing delim (default newline) from each line read.
If the bash4 solution is admissible, then the advice given
e.g. by gniourf_gniourf at reading-output-of-command-into-array-in-bash
is still sound.
I have tried everything I can think of to cut this into separate elements for my array but I am struggling..
Here is what I am trying to do..
(This command just rips out the IP addresses on the first element returned )
$ IFS=$"\n"
$ aaa=( $(netstat -nr | grep -v '^0.0.0.0' | grep -v 'eth' | grep "UGH" | sed 's/ .*//') )
$ echo "${#aaa[#]}"
1
$ echo "${aaa[0]}"
4.4.4.4
5.5.5.5
This shows more than one value when I am looking for the array to separate 4.4.4.4 into ${aaa[0]} and 5.5.5.5 into ${aaa[1]}
I have tried:
IFS="\n"
IFS=$"\n"
IFS=" "
Very confused as I have been working with arrays a lot recently and have never ran into this particular issue.
Can someone tell me what I am doing wrong?
There is a very good example on how to use IFS + read -a to split a string into an array on this other stackoverflow page
How does splitting string to array by 'read' with IFS word separator in bash generated extra space element?
netstat is deprecated, replaced by ss, so I'm not sure how to reproduce your exact problem
I am trying to use xmllint to search an xml file and store the values I need into an array. Here is what I am doing:
#!/bin/sh
function getProfilePaths {
unset profilePaths
unset profilePathsArr
profilePaths=$(echo 'cat //profiles/profile/#path' | xmllint --shell file.xml | grep '=' | grep -v ">" | cut -f 2 -d "=" | tr -d \")
profilePathsArr+=( $(echo $profilePaths))
return 0
}
In another function I have:
function useProfilePaths {
getProfilePaths
for i in ${profilePathsArr[#]}; do
echo $i
done
return 0
}
useProfilePaths
The behavior of the function changes whether I do the commands manually on the command line VS calling them from different function as part of a wrapper script. When I can my function from a wrapper script, the items in the array are 1, compared to when I do it from the command line, it's 2:
$ echo ${#profilePathsArr[#]}
2
The content of profilePaths looks like this when echoed:
$ echo ${profilePaths}
/Profile/Path/1 /Profile/Path/2
I am not sure what the separator is for an xmllint call.
When I call my function from my wrapper script, the content of the first iteration of the for loop looks like this:
for i in ${profilePathsArr[#]}; do
echo $i
done
the first echo looks like:
/Profile/Path/1
/Profile/Path/2
... and the second echo is empty.
Can anyone help me debug this issue? If I could find out what is the separator used by xmllint, maybe I could parse the items correctly in the array.
FYI, I have already tried the following approach, with the same result:
profilePaths=($(echo 'cat //profiles/profile/#path' | xmllint --shell file.xml | grep '=' | grep -v ">" | cut -f 2 -d "=" | tr -d \"))
Instead of using the --shell switch and many pipes, you should use the proper --xpath switch.
But as far of I know, when you have multiple values, there's no simple way to split the different nodes.
So a solution is to iterate like this :
profilePaths=(
$(
for i in {1..100}; do
xmllint --xpath "//profiles[$i]/profile/#path" file.xml || break
done
)
)
or use xmlstarlet:
profilePaths=( $(xmlstarlet sel -t -v "//profiles/profile/#path" file.xml) )
it display output with newlines by default
The problem you're having is related to data encapsulation; specifically, variables defined in a function are local, so you can't access them outside that function unless you define them otherwise.
Depending on the implementation of sh you're using, you may be able get around this by using eval on your variable definition or with a modifier like global for mksh and declare -g for zsh and bash. I know that mksh's implementation definitely works.
Thank you for providing feedback on how I can resolve this problem. After investigating more, I was able to make this work by changing the way I was iterating the content of my 'profilePaths' variable to insert its values into the 'profilePathsArr' array:
# Retrieve the profile paths from file.xml and assign to 'profilePaths'
profilePaths=$(echo 'cat //profiles/profile/#path' | xmllint --shell file.xml | grep '=' | grep -v ">" | cut -f 2 -d "=" | tr -d \")
# Insert them into the array 'profilePathsArr'
IFS=$'\n' read -rd '' -a profilePathsArr <<<"$profilePaths"
For some reason, with all the different function calls from my master script and calls to other scripts, it seemed like the separators were lost along the way. I am unable to find the root cause, but I know that by using "\n" as the IFS and a while loop, it worked like a charm.
If anybody wishes to add more comments on this, you are more than welcome.
I'm using the command grep 3 times on the same line like this
ls -1F ./ | grep / | grep -v 0_*.* | grep -v undesired_result
is there a way to combine them into one command instead of having it to pipe it 3 times?
There's no way to do both a positive search (grep <something>) and a negative search (grep -v <something>) in one command line, but if your grep supports -E (alternatively, egrep), you could do ls -1F ./ | grep / | grep -E -v '0_*.*|undesired_result' to reduce the sub-process count by one. To go beyond that, you'd have to come up with a specific regular expression that matches either exactly what you want or everything you don't want.
Actually, I guess that first sentence isn't entirely true if you have egrep, but building the proper regular expression that correctly includes both the positive and negative parts and covers all possible orderings of the parts might be more frustrating than it's worth...