am in a need of using an array to set the variable value for further manipulations from the output file.
scenario:
> 1. fetch the list from database
> 2. trim the column using sed to a file named x.txt (got specific value as that is required)
> 3. this file x.txt has the below output as
10000
20000
30000
> 4. I need to set a variable and assign the above values to it.
A=10000
B=20000
C=30000
> 5. I can invoke this variable A,B,C for further manipulations.
Please let me know how to define an array assigning to its variable from the output file.
Thanks.
In bash (starting from version 4.x) and you can use the mapfile command:
mapfile -t myArray < file.txt
see https://stackoverflow.com/a/30988704/10622916
or another answer for older bash versions: https://stackoverflow.com/a/46225812/10622916
I am not a big proponent of using arrays in bash (if your code is complex enough to need an array, it's complex enough to need a more robust language), but you can do:
$ unset a
$ unset i
$ declare -a a
$ while read line; do a[$((i++))]="$line"; done < x.txt
(I've left the interactive prompt in place. Remove the leading $
if you want to put this in a script.)
Related
I have a text file with with the following lines of text:
https://i.imgur.com/9iLSS35.png
Delete page: https://imgur.com/delete/SbmZQDht9Xk2NbW
https://i.imgur.com/9iLSS336.png
Delete page: https://imgur.com/delete/SbmZQDht9Xk2NbW
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I need to read the odd lines and add to a array in bash. I have tried the following code but it generates a variable and not an array as I need.
A=$(sed -n 1~2p ./upimagen.txt)
How can I read the odd lines of the text file and add each line to an array and then access separately?
The result would be:
${A[0]}
https://i.imgur.com/9iLSS35.png
${A[1]}
https://i.imgur.com/9iLSS336.png
...
Array assignment requires an outer set of parentheses.
A=($(sed -n 1~2p ./upimagen.txt))
This will split on all whitespace, though, not just newlines. It will also expand any globs that use * or ?. It's better to use readarray plus process substitution to ensure that each line is preserved as is:
readarray -t A < <(sed -n 1~2p ./upimagen.txt)
Just a slight variation on John's answer using awk. Using either readarray or the synonymous mapfile reading from a process substitution is probably your best bet, e.g.
readarray -t A < <(awk 'FNR % 2 {print $1}' ./upimagen.txt)
While there is nothing wrong with the direct initialization using command substitution, e.g. A=( $(...) ), if your files are large, or if you only need part of the range of lines, or say you have a custom function you want to run on every X number of elements read, mapfile/readarray offers a wide set of features over straight command substitution.
Using awk :
readarray -t A < <(awk 'NR%2' ./upimagen.txt)
In bash I have an array with path names, and I would like to replace each of them with different ones using sed, like so:
sed 's#^(.*?)master_repo(.*?)#\1"${SOME_REPO_NAME}"\2#g' <<< ${FULL_TGT_DIRS[${i}]}
A sample path name which is an element of the array would be:
/Volumes/munki/master_repo/pkgs/apps
I would like to replace the path name "master_repo" with for example "somedir", which is stored in $SOME_REPO_NAME, so I get:
/Volumes/munki/somedir/pkgs/apps
Or with built in string substitution:
for i in ${FULL_TGT_DIRS[#]}
do
FULL_TGT_DIRS[$i]=${FULL_TGT_DIRS[$i]/master_repo/$SOME_REPO_NAME}
#sed 's#^(.*?)master_repo(.*?)#\1"${SOME_REPO_NAME}"\2#g' <<< ${FULL_TGT_DIRS[${i}]}
done
I always get the following error when running my script:
> /usr/local/bin/repomgr: line 135:
> /Volumes/munki/master_repo/pkgs/apps: syntax error: operand expected
> (error token is "/Volumes/munki/master_repo/pkgs/apps")
I've tried using different separaters and sed options, as well as shuffling through different quote constellations. I don't write bash scripts on a daily basis so perhaps I'm missing something?
BTW, I run this on a Mac and therefore only have bash 3.2 at my disposal.
There's no need to use sed for this, bash has built-in string replacement in its parameter expansion.
var=/Volumes/munki/master_repo/pkgs/apps
$SOME_REPO_NAME=somedir
newvar=${var/master_repo/$SOME_REPO_NAME}
In a for-in loop, the variable gets set to the array elements, not the array indexes, so you shouldn't be using FULL_TGT_DIRS[$i] -- $i contains the pathname. So the loop should be:
for file in ${FULL_TGT_DIRS[#]}
do
file=${file/master_repo/$SOME_REPO_NAME}
# Do something with $file here
done
If you need to modify the array in place, you need a different loop for the indexes:
for ((i = 0; i < ${#FULL_TGT_DIRS[#]}; i++))
do
FULL_TGT_DIRS[$i]=${FULL_TGT_DIRS[$i]/master_repo/"$SOME_REPO_NAME"}
done
You can even go a step further using bashes own replacement:
for file in "${FULL_TGT_DIRS[#]/master_repo/somedir}"
do
...work on file variable here...
done
I have the following find command with the following output:
$ find -name '*.jpg'
./public_html/github/screencasts-gh-pages/reactiveDataVis/presentation/images/telescope.jpg
./public_html/github/screencasts-gh-pages/introToBackbone/presentation/images/telescope.jpg
./public_html/github/StarCraft-master/img/Maps/(6)Thin Ice.jpg
./public_html/github/StarCraft-master/img/Maps/Snapshot.jpg
./public_html/github/StarCraft-master/img/Maps/Map_Grass.jpg
./public_html/github/StarCraft-master/img/Maps/(8)TheHunters.jpg
./public_html/github/StarCraft-master/img/Maps/(2)Volcanis.jpg
./public_html/github/StarCraft-master/img/Maps/(3)Trench wars.jpg
./public_html/github/StarCraft-master/img/Maps/(8)BigGameHunters.jpg
./public_html/github/StarCraft-master/img/Maps/(8)Turbo.jpg
./public_html/github/StarCraft-master/img/Maps/(4)Blood Bath.jpg
./public_html/github/StarCraft-master/img/Maps/(2)Switchback.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(6)Thin Ice.jpg
./public_html/github/StarCraft-master/img/Maps/Original/Map_Grass.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(8)TheHunters.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(2)Volcanis.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(3)Trench wars.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(8)BigGameHunters.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(8)Turbo.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(4)Blood Bath.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(2)Switchback.jpg
./public_html/github/StarCraft-master/img/Maps/Original/(4)Orbital Relay.jpg
./public_html/github/StarCraft-master/img/Maps/(4)Orbital Relay.jpg
./public_html/github/StarCraft-master/img/Bg/GameLose.jpg
./public_html/github/StarCraft-master/img/Bg/GameWin.jpg
./public_html/github/StarCraft-master/img/Bg/GameStart.jpg
./public_html/github/StarCraft-master/img/Bg/GamePlay.jpg
./public_html/github/StarCraft-master/img/Demo/Demo.jpg
./public_html/github/flot/examples/image/hs-2004-27-a-large-web.jpg
./public_html/github/minicourse-ajax-project/other/GameLose.jpg
How do I store this output in an array? I want it to handle filenames with spaces
I have tried this arrayname=($(find -name '*.jpg')) but this just stores the first element. # I am doing the following which seems to be just the first element?
$ arrayname=($(find -name '*.jpg'))
$ echo "$arrayname"
./public_html/github/screencasts-gh-pages/reactiveDataVis/presentation/images/telescope.jpg
$
I have tried here but again this just stores the 1st element
Other similar Qs
How do I capture the output from the ls or find command to store all file names in an array?
How do i store the output of a bash command in a variable?
If you know with certainty that your filenames will not contain newlines, then
mapfile -t arrayname < <(find ...)
If you want to be able to handle any file
arrayname=()
while IFS= read -d '' -r filename; do
arrayname+=("$filename")
done < <(find ... -print0)
echo "$arrayname" will only show the first element of the array. It is equivalent to echo "${arrayname[0]}". To dump an array:
printf "%s\n" "${arrayname[#]}"
# ............^^^^^^^^^^^^^^^^^ must use exactly this form, with the quotes.
arrayname=($(find ...)) is still wrong. It will store the file ./file with spaces.txt as 3 separate elements in the array.
If you have a sufficiently recent version of bash, you can save yourself a lot of trouble by just using a ** glob.
shopt -s globstar
files=(**/*.jpg)
The first line enables the feature. Once enabled, ** in a glob pattern will match any number (including 0) of directories in the path.
Using the glob in the array definition makes sure that whitespace is handled correctly.
To view an array in a form which could be used to define the array, use the -p (print) option to the declare builtin:
declare -p files
I am able to read file into a regular array with a single statement:
local -a ary
readarray -t ary < $fileName
Not happening is reading a file into assoc. array.
I have control over file creation and so would like to do as simply as possible w/o loops if possible at all.
So file content can be following to be read in as:
keyname=valueInfo
But I am willing to replace = with another string if cuts down on code, especially in a single line code as above.
And ...
So would it be possible to read such a file into an assoc array using something like an until or from - i.e. read into an assoc array until it hits a word, or would I have to do this as part of loop?
This will allow me to keep a lot of similar values in same file, but read into separate arrays.
I looked at mapfile as well, but does same as readarray.
Finally ...
I am creating an options list - to select from - as below:
local -a arr=("${!1}")
select option in ${arr[*]}; do
echo ${option}
break
done
Works fine - however the list shown is not sorted. I would like to have it sorted if possible at all.
Hope it is ok to put all 3 questions into 1 as the questions are similar - all on arrays.
Thank you.
First thing, associative arrays are declared with -A not -a:
local -A ary
And if you want to declare a variable on global scope, use declare outside of a function:
declare -A ary
Or use -g if BASH_VERSION >= 4.2.
If your lines do have keyname=valueInfo, with readarray, you can process it like this:
readarray -t lines < "$fileName"
for line in "${lines[#]}"; do
key=${line%%=*}
value=${line#*=}
ary[$key]=$value ## Or simply ary[${line%%=*}]=${line#*=}
done
Using a while read loop can also be an option:
while IFS= read -r line; do
ary[${line%%=*}]=${line#*=}
done < "$fileName"
Or
while IFS== read -r key value; do
ary[$key]=$value
done < "$fileName"
I'm trying to read the lines of output from a subshell into an array, and I'm not willing to set IFS because it's global. I don't want one part of the script to affect the following parts, because that's poor practice and I refuse to do it. Reverting IFS after the command is not an option because it's too much trouble to keep the reversion in the right place after editing the script. How can I explain to bash that I want each array element to contain an entire line, without having to set any global variables that will destroy future commands?
Here's an example showing the unwanted stickiness of IFS:
lines=($(egrep "^-o" speccmds.cmd))
echo "${#lines[#]} lines without IFS"
IFS=$'\r\n' lines=($(egrep "^-o" speccmds.cmd))
echo "${#lines[#]} lines with IFS"
lines=($(egrep "^-o" speccmds.cmd))
echo "${#lines[#]} lines without IFS?"
The output is:
42 lines without IFS
6 lines with IFS
6 lines without IFS?
This question is probably based on a misconception.
IFS=foo read does not change IFS outside of the read operation itself.
Thus, this would have side effects, and should be avoided:
IFS=
declare -a array
while read -r; do
array+=( "$REPLY" )
done < <(your-subshell-here)
...but this is perfectly side-effect free:
declare -a array
while IFS= read -r; do
array+=( "$REPLY" )
done < <(your-subshell-here)
With bash 4.0 or newer, there's also the option of readarray or mapfile (synonyms for the same operation):
mapfile -t array < <(your-subshell-here)
In examples later added to your answer, you have code along the lines of:
lines=($(egrep "^-o" speccmds.cmd))
The better way to write this is:
mapfile -t lines < <(egrep "^-o" speccmds.cmd)
Are you trying to store the lines of the output in an array, or the words of each line?
lines
mapfile -t arrayname < <(your subshell)
This does not use IFS at all.
words
(your subshell) | while IFS=: read -ra words; do ...
The form var=value command args... puts the var variable into the environment of the command, and does not affect the current shell's environment.