bash,shell,sh , Error on retrieving array length in bash

Error on retrieving array length in bash


Tag: bash,shell,sh

I've been trying to run a simple script that retrieves the penultimate subdirectory of a variable size directory. But it fails miserably to retrieve its length. The script goes:

ARRAY=$(ls files-0/var/log/)

echo ${#ARRAY[@]}

for i in ${#ARRAY[@]};
    echo $i

The output I get is:



If i change the line

for i in ${#ARRAY[@]};


for i in $ARRAY;

at least I get the list of directories/files:


I know there are lot's of posts approaching this question, but mostly all of them start from the basis of getting array length properly.


Following up on the comment, the syntax for initializing indexed array values in BASH is:

array=( element1 element2 etc... )

In your case you were simply assigning the result of the command substitution to the array with:

ARRAY=$(ls files-0/var/log/)

(which assigned the return of ls files-0/var/log/ to a variable named ARRAY)

The proper initialization of the ARRAY using command substitution is:

ARRAY=( $(ls files-0/var/log/) )

Note: when an array is declared with declare -a somename, or after it has been initialized with values, you can add an element to the array in the next open index with:

ARRAY+=( somevalue )  # quoted as necessary

As of BASH 4, you also have Associative Arrays (declare -A) which allow arrays to be created with key value pairs, instead of simple index value pairs. Where initialization is:

AARRAY=( [key1]=value1 [key2]=value2 etc... )

Good luck with BASH, it is a very capable shell.


Delete some lines from text using Linux command

I know how to match text using regex patterns but not how to manipulate them. I have used grep to match and extract lines from a text file, but I want to remove those lines from the text. How can I achieve this without having to write a python or...

Using the shell provided with NodeJS

Once you've installed NodeJS, you'll have a executable in your computer named NodeJS which is a shell. I was wondering what can I do with that... here you're able to run JS code as, for example, in the browser's console, great. Now, is it possible to require modules in that...

bash interactive script pass input

I'm running the following interactive Jar. java -jar script.jar argument-line-here \n Now I'm creating a bash script which runs the jar file. How do I pass the argument line and the conformation "\n" to this interactive script? these are input lines for the script. This question has some answers, expect...

Replace [a-z],[a-z] with [a-z], [a-z] and keep the letters

How can I replace [a-z],[a-z] with [a-z], [a-z] and keeping the letters? Input suny stony brook, stony brook,usa. Output suny stony brook, stony brook, usa. What I have tried sed 's/[a-z],[a-z]/[a-z], [a-z]/g' <<< "suny stony brook, stony brook,usa." sed 's/[a-z],[a-z]/, /g' <<< "suny stony brook, stony brook,usa." ...

Use Unix Executable File to Run Shell Script and MPKG File

I have 2 shell scripts and 2 mpkg installer, I am trying to use an unix excitable file to run them all. here is the script I have, but it always has error message "No such file or directory" ? #!/bin/sh # Find the absolute script current path path=$( cd...

Why does `sort file > file` result in an empty file? [duplicate]

This question already has an answer here: bash redirect input from file back into same file 7 answers When you try to sort a file in-place with sort afile > afile you silently end up with afile being an empty file. Why is that? I'd expect either an error...

AWK write to new column base on if else of other column

I have a CSV file with columns A,B,C,D. Column D contains values on a scale of 0 to 1. I want to use AWK to write to a new column E base in values in column D. For example: if value in column D <0.7, value in column E =...

Bash alias function with predefined argument

I have an alias gl which is an wrapper for git log. Basically like this function gitLog(){ if [ $# -eq 0 ] then git log else git log -n $1 } alias gl=gitLog I want to add an alias which just calls gitLog with an argument like this alias...

print filenames into scripts in bash

How do you print each name of a file from a directory into a string and make make new scripts? to print each file name for i in `ls new_manifest*`; do echo $i; done but when I try and print the rest of the string with $i like this is...

Assign and use of a variable in the same subshell

I was doing something very simple like: v=5 echo "$v" and expected it to print 5. However, it does not. The value that was just set is not available for the next command. I recently learnt that "In most shells, each command of a pipeline is executed in a separate...

Why can I view some Unix executable files in Mac OS X and not others?

I am on a Macbook Pro on Mac OS X 10.10 (Yosemite). When I go to /usr/bin, git is there as a unix executable file. When I open it up in Sublime Text, all I get is unreadable machine code. However, when I open up a different Unix executable fileā€”in...

Identifying when a file is changed- Bash

So in my bash shell script, I have it running through a for loop. Inside the for loop, I use find "$myarray[i]" >> $tmp to look for a certain directory each time through the loop. Sometimes, it finds the variable in myarray[i] and sometimes it doesn't. When it does find...

Bash script using sed acts differently when passing variable

I have a script that I am writing that checks a value and then based on the value modifies it. I am trying to understand why it works this one way and not the other. Based on the google and stackoverflow searches I did, nothing really fits what I am...

How to extract first letters of dashed separated words in a bash variable?

I would like to extract the first letter of dashed separated words value of my bash variable, like this: MY_TEXT=this-is-my-custom-text I would like to create a second variable like this: MY_INITIALS=timct...

While loop in bash using variable from txt file

I am new to bash and writing a script to read variables that is stored on each line of a text file (there are thousands of these variables). So I tried to write a script that would read the lines and automatically output the solution to the screen and save...

Bash script that removes C source comments

I need to write a bash script which copies all .c files from a directory $2 to another directory $1, but without comments. I only have to remove comments that begin with //, might have tabs/spaces before the comment, but not letters. Also, I need to do it with only...

How do I align my output?

I'm writing a script that takes a parameter and reads the output of ls -l. It then displays the user and the name of the file STARTING with that parameter. For example : $> ls -l | ./ "o" John ok_test RandomUser o_file My script works just fine, but I...

How to extract single-/multiline regex-matching items from an unpredictably formatted file and put each one in a single line into output file?

I have a very huge file which looks like this: <a>text</a>text blah <b>data1</b>abc<b>data2</b> <b>data3</b>blahblah <c>text</c> <d>text</d> <x>blahblah<b>data4 data5 data6</b> <b>data7 </x> That is, its formatting is unpredictable. I need to extract each <b>...</b> item (it might contain multiline text!) and put every one of them in a single separate line....

AWK count number of times a term appear with respect to other columns

Given a CSV file: id, fruit, binary 1, apple, 1 2, orange, 0 3, pear, 1 4, apple, 0 5, peach, 0 6, apple, 1 How can i calculate for each unique values in fruit, the number of times the binary value =1 / number of occurences of that fruit...

Extra backslash when storing grep in a value

In a bash script I have: Check="grep -e '"'\(-S mount\)'"' /etc/audit/audit.rules" set -x When you run it it shows it as: CHECK='grep -e '\''\(-S mount\)'\'' /etc/audit/audit.rules' Now it works exactly what I want but I want to understand it. Why is there 2 extra \'s?...

How do I check whether a file or file directory exist in bash?

I currently have this bash script (which is located in my home directory, i.e., /home/fusion809/ and I am running it as root as it's necessary for the icon copying lines): cd /home/fusion809/Pictures/Icon* declare -a A={Arch,Debian,Fedora,Mageia,Manjaro,OpenSUSE} declare -a B={Adwaita,Faenza,gnome,Humanity} for i in $A; do for j in $B; do if test...

shell script for counting replacements

Ten files located in a directory. Each file content has "apple" word. write a bash shell script to replace "apple" with "banana" in all ten files and Print the number of replacements for each file. Have tried in this way but dont know how to get number of replacement. can...

Macports switch PHP CLI version

I'm trying to switch my Terminal PHP version to 5.4 because I ran into some issues with Drush while updating my Drupal core. The reason for these issues is my Terminal PHP version is different then my localhost. php -v in Terminal returns PHP 5.5.13 (cli) but my localhost...

using sed to replace a line with back slashes in a shell script

I am trying to replace the bottom one of these 2 lines with sed in a file. <rule>out_prefix=orderid ^1\\d\+ updatemtnotif/</rule>\n\ <rule>out_prefix=orderid ^2\\d\+ updatemtnotif/</rule>\n\ And the following command seems to do that when executed as a command at the bash prompt sed -i '[email protected]_prefix=orderid ^2\\\\d\\+ updatemtnotif/@out_prefix=orderid ^2\\\\d\\+ updatemtnotif_fr/@g' /opt/temp/rules.txt however, when...

How to change svn:externals from bash file non-interactive

I have multi externals need to be set within a file externals.txt and I attempt to change the svn:externals from a bash: svn pe svn:externals svn://hostname/branchname -F extenals.txt But the command throws out an error: svn: E205007: None of the environment variables SVN_EDITOR, VISUAL or EDITOR are set, and no...

linux - running a process and tailing a file simultaneously

I want a run a long task on a remote machine (with python fabric using ssh). It logs to a file on the remote machine. What I want to do is to run that script and tail (actively display) the log file content until the script execution ends. The problem...

AWK|BASH, use double FS and ternary operator

Is it possible? I was wondering how to do: Count fields differentiated by comma. Only the obtained first field of the previous step, count words differentiated by space. If there is more than 2 words, print NF, otherwise $0. Input cellular biol immunogenet, rosario escuela estadist, medellin medellin Expected output...

Bash modify CSV to change a field

I have a very big CSV file (aprox. 10.000 rows and 400 columns) and I need to modify certain columns (like 15, 156, 220) to change format from 20140321132233 to 2014-03-21 13:22:33. All fields that I need to modify are datetime. I saw some examples using awk but for math...

How do I silence the HEAD of a curl request while using the silent flag?

When I run the curl command and direct the data to a file, I get back the content of the site as expected. $ curl "" > file.txt $ head file.txt Top of site ... However, this command shows a progress bar, which I do not want: % Total %...

shell script cut from variables

The file is like this aaa&123 bbb&234 ccc&345 aaa&456 aaa$567 bbb&678 I want to output:(contain "aaa" and text after &) 123 456 I want to do in in shell script, Follow code be consider #!/bin/bash raw=$(grep 'aaa' 1.txt) var=$(cut -f2 -d"&" "$raw") echo $var It give me a error like...

Missing one condition to display a string

I am working on a small script that simply takes a parameter and read the output of ls -l and displays the user and name of the file that start with that parameter. For exemple : $> ls -l | ./ "ok" John ok_file Mark ok_test Here is what the...

Capitalize all files in a directory using Bash

I have a directory called "Theme_1" and I want to capitalize all the filenames starting with "theme". The first letter of every file name is lowercase and I want it to be upcase. I've tried this but all the letters in the filename are upcase, which is not what I...

how to modify an array value with given index?

I want to modify an array cell, which I can do when I know the cell as a number. However here my cell position is given by $i. pomme[`${i}`]="" I tried without the `` and it doesn't work either? How am I suppose to do it?...

How to test if a command is a shell reserved word?

I am writing a bash script and I would like to verify if a string is a shell reserved word (like if, for, alias, etc...). How can I can do this?...

how to deletes line from a text file that are taken from another file [duplicate]

This question already has an answer here: Remove duplicates from text file based on second text file 4 answers I have a data.txt file with a lot of lines in it and a lines.txt that contains some lines. I want to delete all lines from data.txt that match any...

How to append entry the end of a multi-line entry using any of stream editors like sed or awk

I am trying to use a script to append the host name at the end of a multi-line entry of a specific Host_Alias field in sudoers file. The current sudoers file has an entry similar to : Host_Alias srv_linuxestate= \ host10,host12,host13,host1,host50,\ host16,host1,host2,host11,host15,host21,\ host3,host14 My required output would be something like...

Matching string inside file and returning result

I've got a few peculiar issues with trying to search for a string inside of a .db file. The way I tried was by using grep, which does apparently find the string(s), although this is the output: $ grep "ext" *.db Binary file enormous.db matches There are a couple problems...

Linux-wget command

I need a quick help on customizing my wget command in a shell script: The wget command looks something like this: wget http://infamvn:8081/nexus/content/groups/LDM_REPO_LIN64/com/infa/com.infa. products.ldm.ingestion.server.scala/ Here I'd like to add the in a variable, so I created a script something like this: n = wget...

Python: can't access newly defined environment variables

I can't access my env var: import subprocess, os print os.environ.get('PATH') # Works well print os.environ.get('BONSAI') # doesn't work But the env var is well added in my /home/me/.bashrc: BONSAI=/home/me/Utils/bonsai_v3.2 export BONSAI And I can access this env var from a new terminal....

Aggregate failure codes in bash

I've got a script which has multiple stages, and at each stage it's possible to fail, but the script can carry on running. Concretely, I generate some json, and check if the diff is correct. The diff could be wrong, but it doesn't stop the next stage of json being...