In bash, I would like to loop over a previously defined array, which contains filenames. In turn, each file of the array must be readed and processed dynamically (while read line...).
This is an example of what the files of the array contains:
_VALUE1_,_VALUE1_,1,Name 1
_VALUE2_,_VALUE2_,1,Name 2
_VALUE3_,_VALUE3_,1,Name 3
_VALUE4_,_VALUE4_,1,Name 4
_VALUE5_,_VALUE5_,1,Name 5
This is what I've tested with no luck.
#!/bin/bash
. functions.sh
GEN_ARQ_ARRAY=("./cfg_file.txt" "./euro_file.txt" "./zl_file.txt")
WB_ARQ_ARRAY=("./rn_cfg_wb_file.txt" "./rn_eur_wb_file.txt" "./rn_zl_wb_file.txt")
BN_ARQ_ARRAY=("./rn_cfg_bn_file.txt" "./rn_eur_bn_file.txt" "./rn_zl_bn_file.txt")
AM_ARQ_ARRAY=("./rn_cfg_am_file.txt" "./rn_eur_am_file.txt" "./rn_zl_am_file.txt")
STATUS_BOOL=true
for i in "${!GEN_ARQ_ARRAY[#]}"; do
while IFS=$'\r' read -r line || [[ -n "$line" ]];do
STACK_NAME=${line%%,*} # Gets the first substring of a string divided by ','
STACK_STATUS=$(curl -su "${USERNAME}":"${PASSWORD}" -X GET http://"${SERVER_NAME}":9100/api/stacks/"${STACK_NAME}"/state | ./jq-linux64 -cr '.result.value')
if [[ $(echo "$STACK_STATUS" | tr -d '\r') == "$STATUS_BOOL" ]]; then
echo "${line}" >> "${GEN_ARQ_ARRAY[i]}"
case ${line} in
*"ARQBS"*|*"ARCBS"*|*"ARQWB"*|*"ARCWB"*) echo "${line}" >> "${WB_ARQ_ARRAY[$i]}";;
*"ARQOF"*|*"ARCOF"*|*"ARQBN"*|*"ARCBN"*) echo "${line}" >> "${BN_ARQ_ARRAY[$i]}";;
*"ARQAM"*|*"ARCAM"*) echo "${line}" >> "${AM_ARQ_ARRAY[$i]}";;
*) echo "$(logWarn) No matches -- ${STACK_NAME}" | tee -a "$LOGFILE";;
esac
else
echo "$(logInfo) ${STACK_NAME} is not running" | tee -a "$LOGFILE"
fi
done < "${GEN_ARQ_ARRAY[i]}"
done
Problem here is that the for loop starts, detects array content, gets the first value of the array, enter into while, and it constantly loops in the first position of the array even with the end of the file is reached. I can't find the way to exit the while loop and continue with the next array position.
I'm pretty sure there is a better way to implement this.
Hearing your ideas!
Edit:
Solved by replacing the line echo "${line}" >> "${GEN_ARQ_ARRAY[i]}", which was in-loop filling up the file.
Solved by replacing the line echo "${line}" >> "${GEN_ARQ_ARRAY[i]}", which was in-loop filling up the file. Once I did, the code worked flawlessly.
In the following program, if I set the variable $foo to the value 1 inside the first if statement, it works in the sense that its value is remembered after the if statement. However, when I set the same variable to the value 2 inside an if which is inside a while statement, it's forgotten after the while loop. It's behaving like I'm using some sort of copy of the variable $foo inside the while loop and I am modifying only that particular copy. Here's a complete test program:
#!/bin/bash
set -e
set -u
foo=0
bar="hello"
if [[ "$bar" == "hello" ]]
then
foo=1
echo "Setting \$foo to 1: $foo"
fi
echo "Variable \$foo after if statement: $foo"
lines="first line\nsecond line\nthird line"
echo -e $lines | while read line
do
if [[ "$line" == "second line" ]]
then
foo=2
echo "Variable \$foo updated to $foo inside if inside while loop"
fi
echo "Value of \$foo in while loop body: $foo"
done
echo "Variable \$foo after while loop: $foo"
# Output:
# $ ./testbash.sh
# Setting $foo to 1: 1
# Variable $foo after if statement: 1
# Value of $foo in while loop body: 1
# Variable $foo updated to 2 inside if inside while loop
# Value of $foo in while loop body: 2
# Value of $foo in while loop body: 2
# Variable $foo after while loop: 1
# bash --version
# GNU bash, version 4.1.10(4)-release (i686-pc-cygwin)
echo -e $lines | while read line
...
done
The while loop is executed in a subshell. So any changes you do to the variable will not be available once the subshell exits.
Instead you can use a here string to re-write the while loop to be in the main shell process; only echo -e $lines will run in a subshell:
while read line
do
if [[ "$line" == "second line" ]]
then
foo=2
echo "Variable \$foo updated to $foo inside if inside while loop"
fi
echo "Value of \$foo in while loop body: $foo"
done <<< "$(echo -e "$lines")"
You can get rid of the rather ugly echo in the here-string above by expanding the backslash sequences immediately when assigning lines. The $'...' form of quoting can be used there:
lines=$'first line\nsecond line\nthird line'
while read line; do
...
done <<< "$lines"
UPDATED#2
Explanation is in Blue Moons's answer.
Alternative solutions:
Eliminate echo
while read line; do
...
done <<EOT
first line
second line
third line
EOT
Add the echo inside the here-is-the-document
while read line; do
...
done <<EOT
$(echo -e $lines)
EOT
Run echo in background:
coproc echo -e $lines
while read -u ${COPROC[0]} line; do
...
done
Redirect to a file handle explicitly (Mind the space in < <!):
exec 3< <(echo -e $lines)
while read -u 3 line; do
...
done
Or just redirect to the stdin:
while read line; do
...
done < <(echo -e $lines)
And one for chepner (eliminating echo):
arr=("first line" "second line" "third line");
for((i=0;i<${#arr[*]};++i)) { line=${arr[i]};
...
}
Variable $lines can be converted to an array without starting a new sub-shell. The characters \ and n has to be converted to some character (e.g. a real new line character) and use the IFS (Internal Field Separator) variable to split the string into array elements. This can be done like:
lines="first line\nsecond line\nthird line"
echo "$lines"
OIFS="$IFS"
IFS=$'\n' arr=(${lines//\\n/$'\n'}) # Conversion
IFS="$OIFS"
echo "${arr[#]}", Length: ${#arr[*]}
set|grep ^arr
Result is
first line\nsecond line\nthird line
first line second line third line, Length: 3
arr=([0]="first line" [1]="second line" [2]="third line")
You are asking this bash FAQ. The answer also describes the general case of variables set in subshells created by pipes:
E4) If I pipe the output of a command into read variable, why
doesn't the output show up in $variable when the read command finishes?
This has to do with the parent-child relationship between Unix
processes. It affects all commands run in pipelines, not just
simple calls to read. For example, piping a command's output
into a while loop that repeatedly calls read will result in
the same behavior.
Each element of a pipeline, even a builtin or shell function,
runs in a separate process, a child of the shell running the
pipeline. A subprocess cannot affect its parent's environment.
When the read command sets the variable to the input, that
variable is set only in the subshell, not the parent shell. When
the subshell exits, the value of the variable is lost.
Many pipelines that end with read variable can be converted
into command substitutions, which will capture the output of
a specified command. The output can then be assigned to a
variable:
grep ^gnu /usr/lib/news/active | wc -l | read ngroup
can be converted into
ngroup=$(grep ^gnu /usr/lib/news/active | wc -l)
This does not, unfortunately, work to split the text among
multiple variables, as read does when given multiple variable
arguments. If you need to do this, you can either use the
command substitution above to read the output into a variable
and chop up the variable using the bash pattern removal
expansion operators or use some variant of the following
approach.
Say /usr/local/bin/ipaddr is the following shell script:
#! /bin/sh
host `hostname` | awk '/address/ {print $NF}'
Instead of using
/usr/local/bin/ipaddr | read A B C D
to break the local machine's IP address into separate octets, use
OIFS="$IFS"
IFS=.
set -- $(/usr/local/bin/ipaddr)
IFS="$OIFS"
A="$1" B="$2" C="$3" D="$4"
Beware, however, that this will change the shell's positional
parameters. If you need them, you should save them before doing
this.
This is the general approach -- in most cases you will not need to
set $IFS to a different value.
Some other user-supplied alternatives include:
read A B C D << HERE
$(IFS=.; echo $(/usr/local/bin/ipaddr))
HERE
and, where process substitution is available,
read A B C D < <(IFS=.; echo $(/usr/local/bin/ipaddr))
Hmmm... I would almost swear that this worked for the original Bourne shell, but don't have access to a running copy just now to check.
There is, however, a very trivial workaround to the problem.
Change the first line of the script from:
#!/bin/bash
to
#!/bin/ksh
Et voila! A read at the end of a pipeline works just fine, assuming you have the Korn shell installed.
This is an interesting question and touches on a very basic concept in Bourne shell and subshell. Here I provide a solution that is different from the previous solutions by doing some kind of filtering. I will give an example that may be useful in real life. This is a fragment for checking that downloaded files conform to a known checksum. The checksum file look like the following (Showing just 3 lines):
49174 36326 dna_align_feature.txt.gz
54757 1 dna.txt.gz
55409 9971 exon_transcript.txt.gz
The shell script:
#!/bin/sh
.....
failcnt=0 # this variable is only valid in the parent shell
#variable xx captures all the outputs from the while loop
xx=$(cat ${checkfile} | while read -r line; do
num1=$(echo $line | awk '{print $1}')
num2=$(echo $line | awk '{print $2}')
fname=$(echo $line | awk '{print $3}')
if [ -f "$fname" ]; then
res=$(sum $fname)
filegood=$(sum $fname | awk -v na=$num1 -v nb=$num2 -v fn=$fname '{ if (na == $1 && nb == $2) { print "TRUE"; } else { print "FALSE"; }}')
if [ "$filegood" = "FALSE" ]; then
failcnt=$(expr $failcnt + 1) # only in subshell
echo "$fname BAD $failcnt"
fi
fi
done | tail -1) # I am only interested in the final result
# you can capture a whole bunch of texts and do further filtering
failcnt=${xx#* BAD } # I am only interested in the number
# this variable is in the parent shell
echo failcnt $failcnt
if [ $failcnt -gt 0 ]; then
echo $failcnt files failed
else
echo download successful
fi
The parent and subshell communicate through the echo command. You can pick some easy to parse text for the parent shell. This method does not break your normal way of thinking, just that you have to do some post processing. You can use grep, sed, awk, and more for doing so.
I use stderr to store within a loop, and read from it outside.
Here var i is initially set and read inside the loop as 1.
# reading lines of content from 2 files concatenated
# inside loop: write value of var i to stderr (before iteration)
# outside: read var i from stderr, has last iterative value
f=/tmp/file1
g=/tmp/file2
i=1
cat $f $g | \
while read -r s;
do
echo $s > /dev/null; # some work
echo $i > 2
let i++
done;
read -r i < 2
echo $i
Or use the heredoc method to reduce the amount of code in a subshell.
Note the iterative i value can be read outside the while loop.
i=1
while read -r s;
do
echo $s > /dev/null
let i++
done <<EOT
$(cat $f $g)
EOT
let i--
echo $i
How about a very simple method
+call your while loop in a function
- set your value inside (nonsense, but shows the example)
- return your value inside
+capture your value outside
+set outside
+display outside
#!/bin/bash
# set -e
# set -u
# No idea why you need this, not using here
foo=0
bar="hello"
if [[ "$bar" == "hello" ]]
then
foo=1
echo "Setting \$foo to $foo"
fi
echo "Variable \$foo after if statement: $foo"
lines="first line\nsecond line\nthird line"
function my_while_loop
{
echo -e $lines | while read line
do
if [[ "$line" == "second line" ]]
then
foo=2; return 2;
echo "Variable \$foo updated to $foo inside if inside while loop"
fi
echo -e $lines | while read line
do
if [[ "$line" == "second line" ]]
then
foo=2;
echo "Variable \$foo updated to $foo inside if inside while loop"
return 2;
fi
# Code below won't be executed since we returned from function in 'if' statement
# We aready reported the $foo var beint set to 2 anyway
echo "Value of \$foo in while loop body: $foo"
done
}
my_while_loop; foo="$?"
echo "Variable \$foo after while loop: $foo"
Output:
Setting $foo 1
Variable $foo after if statement: 1
Value of $foo in while loop body: 1
Variable $foo after while loop: 2
bash --version
GNU bash, version 3.2.51(1)-release (x86_64-apple-darwin13)
Copyright (C) 2007 Free Software Foundation, Inc.
Though this is an old question and asked several times, here's what I'm doing after hours fidgeting with here strings, and the only option that worked for me is to store the value in a file during while loop sub-shells and then retrieve it. Simple.
Use echo statement to store and cat statement to retrieve. And the bash user must chown the directory or have read-write chmod access.
#write to file
echo "1" > foo.txt
while condition; do
if (condition); then
#write again to file
echo "2" > foo.txt
fi
done
#read from file
echo "Value of \$foo in while loop body: $(cat foo.txt)"
Before you get concerned, this (hopefully) isn't another of the many threads about having variable access problems from a while loop in BASH. I looked at those and implemented the redirect method, but I'm having some issues.
Code:
#!/bin/bash
rm /tmp/sched.now
rm /tmp/sched.later
NOWURL="schedNOWurl"
LATERURL="schedLATERurl"
curl -s $NOWURL --output /tmp/sched.now
curl -s $LATERURL --output /tmp/sched.later
re='^[0-9]+$'
if grep -q 'no shifts' /tmp/sched.now ; then
nowpeople[0]="No Shifts Assigned For This Time"
nowtime[0]="Now"
else
while read line
do
if [[ ${line:0:1} =~ $re ]] ; then
nowtime[$nowcount]=$line
((nowcount++))
elif [[ ${line:0:1} == '-' ]] ; then
nowpeople[$nowcount]=$line
((nowcount++))
fi
done < /tmp/sched.now
fi
declare -a latertime
declare -a laterpeople
if grep -q 'no shifts' /tmp/sched.later ; then
laterpeople[0]="No Shifts Assigned For This Time"
latertime[0]="Until 23:59"
else
while read line
do
if [[ ${line:0:1} =~ $re ]] ; then
latertime[$latercount]=$line
((latercount++))
elif [[ ${line:0:1} == '-' ]] ; then
laterpeople[$latercount]=$line
((latercount++))
fi
done < /tmp/sched.later
fi
echo ${nowpeople[#]}
echo ${nowtime[#]}
echo ${laterpeople[#]}
echo ${latertime[#]}
The URLs that I'm getting are HTML files. The text I'm attempting to pull in the loops looks something like this
11a-1:30p
- John Doe
with some HTML thrown above and below it. Note that these are all on their own lines.
The issue I'm facing is that the loops aren't saving all of the matches to the array. In the second loop, it should pull three entries into each array. Right now it pulls one with malformed text as follows:
- John Doe
1:30p-4pp
Notice the missing m in pm and the replaced m with a p in pp.
The strange thing is that if I echo $line before the array statement, the line is pulled from the file fine, so it sounds like it's something in the way I'm saving to the array.
Suggestions? Please let me know if you need more details.
I have a flat file which contains the following
INDIA USA SA NZ AUS ARG GER BRA
so there are eight columns altogether . Now I want to store the indexes of those columns only which starts with A into an array.
For that I tried the following statement
awk '{for(i=1;i<=NF;i++){if($i~/^A/){set -A newArray $i}}}' testUnix.txt
when I echo the file using
echo "${newArray[*]}"
it's printing 5 6 but whenever I am trying to get the length of that array
echo ${#newArray[#]}
its length is being shown as 1 only. Should not it be 2 ?
I also tried
awk '{y = 0;for(i=1;i<=NF;i++){if($i~/^A/){newArray[y] = $i ; y++}}}' testUnix.txt
but also it's producing the same result.
What am I missing ?Please explain. I intend to get the desired output 2.
No need for awk. You can loop through the elements and check if they start with A:
r="INDIA USA SA NZ AUS ARG GER BRA"
arr=()
for w in $r
do
[[ $w == A* ]] && arr+=("$w")
done
If you execute it then the arr array contains:
$ for i in "${arr[#]}"; do echo "$i"; done
AUS
ARG
And to confirm that is has two elements, let's count them:
$ echo "${#arr[#]}"
2
What is happening with your aproach?
awk '{for(i=1;i<=NF;i++){if($i~/^A/){set -A newArray $i}}}' testUnix.txt
this says set -A newArray but it is not really defining the variable in bash, because you are in awk.
What I would do to have a bash array :
bash_arr=( $(awk '{for(i=1;i<=NF;i++){if($i~/^A/){print $i}}}' file) )
echo "${bash_arr[#]}"
AUS ARG
And you don't even need awk in reality, bash is capable of doing regex :
for word in $(<file); do [[ $word =~ ^A ]] && basharr+=( "$word" ); done
Posted my code below, wondering if I can search one array for a match... or if theres a way I can search a unix file inside of an argument.
#!/bin/bash
# store words in file
cat $1 | ispell -l > file
# move words in file into array
array=($(< file))
# remove temp file
rm file
# move already checked words into array
checked=($(< .spelled))
# print out words & ask for corrections
for ((i=0; i<${#array[#]}; i++ ))
do
if [[ ! ${array[i]} = ${checked[#]} ]]; then
read -p "' ${array[i]} ' is mispelled. Press "Enter" to keep
this spelling, or type a correction here: " input
if [[ ! $input = "" ]]; then
correction[i]=$input
else
echo ${array[i]} >> .spelled
fi
fi
done
echo "MISPELLED: CORRECTIONS:"
for ((i=0; i<${#correction[#]}; i++ ))
do
echo ${array[i]} ${correction[i]}
done
otherwise, i would need to write a for loop to check each array indice, and then somehow make a decision statement whether to go through the loop and print/take input
The ususal shell incantation to do this is:
cat $1 | ispell -l |while read -r ln
do
read -p "$ln is misspelled. Enter correction" corrected
if [ ! x$corrected = x ] ; then
ln=$corrected
fi
echo $ln
done >correctedwords.txt
The while;do;done is kind of like a function and you can pipe data into and out of it.
P.S. I didn't test the above code so there may be syntax errors