Questions about shell scripts, executable files that are interpreted by a shell (bash, zsh, etc.).

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List info about files/directories with spaces

I am trying to use ls to get information about files and directories. My current command fails to properly get the name whenever a file/directory has a space. I am using this to list all ...
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1answer
82 views

Social website about shell commands

I remember seeing an entire social website devoted to the question What are your favorite command line features or tricks?, where you can post shell commands, tag them, comment on them, and rate ...
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952 views

Remove all packages in a text file via apt-get

I have a text file with a package on each line. How can I remove all the packages in that text file from the system? Also, if one package cannot be removes/wasn't installed in the first place can I ...
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758 views

Create MySQL database name using variable from date

for the variable dbnya="echo $(date +%Y%m%d%H%M%S)" When running below code, I will get an error (SQL syntax error) mysql -u root -pthepass -e "CREATE DATABASE demo$dbnya CHARACTER SET utf8 ...
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95 views

Can someone clarify: 'case “:$PATH:” in' in script?

I am not an expert at Unix scripting. An answer to another question suggests using the following piece of code in a script: case ":$PATH:" in *:$HOME/mydir:*) echo it is in the path;; *) echo not ...
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166 views

How to log if an environment variable is unset? [closed]

How can I write a shell script that checks for an environment variable and writes to a log file if the variable is unset? Also, if the file name pointed by env variable doesn't exist, how to create ...
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1answer
1k views

Taking output of /dev/tty into a variable

I created a two backup scripts - one for files (filebackup.sh) and another for database (dbbackup.sh). filebackup.sh calls dbbackup.sh and stores the output in a variable. The output returned by ...
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65 views

Need output in a good format using shell script

I have a file, PoolReport.txt. Here is some sample data: Thu, Aug 27, 2015 7:56:29 AM PoolName,Total GB,Used GB ,Available GB ,Percent Full Oracle-RAID10,6432.539,6179.295,253.244,96.063 ...
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50 views

Job control over a Bash script

I have a Bash script of a thousand lines each containing an ffmpeg command. I start this with source script and it runs just fine. However, when I try to take control of this script in various ways, ...
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49 views

How to print the line numbers with corresponding line that matches a pattern using shell command? [duplicate]

File, .false alarm is bla no. 11 .no alarm generated is bla .application will be killed is bla wall command .doc file is document file with .doc extension .no authority for this selection bla Now ...
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97 views

change of date format in awk command

I have a file mdn.txt with following sample record. mdn.txt: 123456,2711448,1,20150214092425,20150714092425,120,20150814163821,,123,,,123,20150214092425,,123,,,123,20150214092425,,123,Y Now I want ...
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45 views

How to use sed to replace keys in a file using a regex?

I would like to modify a file to replace keys, suppose these keys are in the file as: 42NM 52NM 23NO XNNM I would like to replace anything with NM, with the word "Okay". 1 #!bin/bash/ 2 3 if [ ...
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72 views

What's the most efficient way to log crontab shell script errors with error occurred time?

A common way to log crontab task errors looks like below: 1 */8 * * * sh /pseudo_path/test.sh 2>> my_err_log It's a concise command, but it can't record the error occurred time, and the path ...
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154 views

How to pass variables to awk command with conditions?

I have a while loop which reads data from a file with city names: city_name: COIMBATORE MADURAI PONDICHERRY SALEM TRIPUR TIRUCHI TIRUNELVELI TUTUCORIN VELLORE and using an awk command within the ...
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49 views

How can I un-write protect file made by tee?

I have a small program and I want to ensure that it works on both write protected files and un-write protected files. So, instead of using echo $text > $file or echo $text >> $file, I am ...
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83 views

“Argument list too long” in for loop

My shell script look like this: #!/bin/bash for file in *.fasta do signalp $file > $file.txt done In the working folder I have 18.000 .fasta files. I want to run each through the signalp ...
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43 views

Trying to store the output of file command into a variable , but the output says “no such file exists”?

This is my shell script: $EXTENSION=$(file $RADIOOUT) $RADIOOUT contains the file name along with its path. output is: ./zenityentry: line 40: =/home/jeevan/Downloads/p.txt:: No such file or ...
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What does colon (':') in bash variable resolution syntax mean? [duplicate]

Could you help me decode this assignment: jvm_xmx=${jvm_xmx:-1024} Can't understand, what it does.
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58 views

Can someone explain this tail + line to me?

I'm looking through some of the scripts that are on the servers and came across an 80MB shell script. Naturally curious I decided to look in there and came across this line: tail +4802 $0 | zcat - | ...
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1answer
76 views

Improving performance of script [closed]

I have been working on a script that can be used to automatically restart my Zabbix monitoring services in the event that they stop running. I have the script working just fine, but figured it could ...
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2answers
60 views

concatenating file names in a variable

I am attempting concatenate file names to use in a ftp mdelete command. Each file name needs to be separated by a space in order for the mdelete command to work. The $i variable is in a loop and I ...
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30 views

Why does this script give error?

Why does this script give error? #!/bin/bash # This script checks whether # the current user is root or # not. if [ $UID -ne 0 ] then echo "Non-root user." else echo "Root user." Fi ...
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318 views

How to see if the directory exists?

How can I check if /bin/x86_64/bin/ls is a directory in a bash shell script Here is what I tried: #!/bin/bash if [ $# -eq 2 ]; then if [[ "$1" = /* ]] then cd ./bin/x86_64/bin/ls ...
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61 views

Substrings in shell script

Am trying to get a substring from a string but am getting the error: ${curr_rec:3:4}: bad substitution #!/bin/ksh get_file_totals() { if [ -e "$file_name" ] then IFS='' ...
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49 views

Url Decoding shell script

How can I store the url-decoded string in a variable using shell script #!/bin/sh alias urldecode='python -c "import sys, urllib as ul;print ul.unquote_plus(sys.argv[1])"' ...
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376 views

Is there any way to send sms to a mobile number using shell script?

I want to send sms periodically to certain Mobile numbers (Indian mobile numbers.) Is there way I can send with my own cellphone number or by creating account in sites like way2sms , etc. Thanks in ...
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315 views

Debian: umount /media/usb0: “Operation not permitted”

I recently moved from Ubuntu 14.10 to Debian Testing. Under Ubuntu I had a shell script for backing up my home folder to a USB stick. The last line of the script unmounts the USB stick. Adapting it to ...
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234 views

How to Prompt the user to press Enter to Exit in terminal so that the terminal doesn't close automatically?

Here is my Port.sh file echo 'Give me a maximum of 5 seconds to run please.' lsof -i | grep Xvnc | grep ESTABLISHED | grep $USER lsof -i | grep $USER | grep Xvnc | grep -o -P '(?<=:).*(?=->)' ...
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1answer
81 views

Indented here document causes a syntax error

I have the following code fragment in my shell script and have a bug that I can't seem to pin down a reason for despite some research. When I run the code as below the script exits with a message ...
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27 views

Substituting file extensions on a variable

I'd like to do the following : create a .tex and directly show it after compilation with evince, ideally it would be like this: showpdf file.tex so I wrote #!/bin/sh pdflatex $1 && ...
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202 views

Bash: Looping through a string

I have a variable Vmac that stores values of multiple MAC addresses, collected from wmic call as follows: Vmac=`wmic --delimiter="," --authentication-file=/path/to/file //IP-ADDR "Select ...
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287 views

How to convert bash shell script to Markdown?

Imagine one has been working on a bunch of deploy scripts. These shells scripts are heavily documented with comments and links and are meant to be read by humans. Wouldn't it be handy to convert ...
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521 views

How do I wait for a file in the shell script?

I'm trying to write a shell script that will wait for a file to appear in the /tmp directory called sleep.txt and once it is found the program will cease, otherwise I want the program to be in a sleep ...
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3answers
378 views

How to pass an array to a function as an actual parameter rather than a global variable

Is there a way to pass an array to a function as one of its parameters? Currently I have #!/bin/bash highest_3 () { number_under_test=(${array[@]}) max_of_3=0 for ((i = 0; ...
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1answer
107 views

split line based on space and delete the second part

I have a big file >fid|29290408|locus|VBIEntCas2262_0001| Phosphoglycolate phosphatase (EC 3.1.3.18) [Enterococcus casseliflavus EC20] ...
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308 views

Why do I get Illegal number: {1..3}

Why am I getting ./6_sum_square_difference.sh: 11: ./6_sum_square_difference.sh: Illegal number: {1..3} for #!/bin/sh summing () { the_total=0 num_in=$1 for one_num in {1..$num_in} do ...
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49 views

Computing differences of column entries

I have a textfile with: 1 100 2 80 3 70 4 64 Now I need another file that contains the first column equal to above and the second column should be the difference of to consecutive values of the ...
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125 views

How to use process substitution within a case statement without getting syntax errors?

I have a script loaded as a service in /etc/init.d/myfile When I try to start the service I get the error /etc/init.d/myservice: 21: /etc/init.d/myservice: Syntax error: "(" unexpected The issue ...
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72 views

Modifying part of a string in bash script

I have a file named variables.f90 , having many lines defining different variables, as follows :: integer::n_monomer=6800 real*8::rx=5.0d0 #... randomly integer and real numbers defined ...
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217 views

iterate over file and send lines as positional parameters to another file

I would like to iterate through a file containing dates (named dates.txt) in the following format: 2009 08 03 08 09 2009 08 03 09 10 2009 08 03 10 11 2009 08 03 11 12 2009 08 03 12 13 2009 08 03 13 ...
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89 views

Creating a list of files, removing “duplicates” with different suffix

I have a problem that (I think) require a bit of script-magic - not sure what would be best though... I have one directory with lots pictures in different formats - jpg, gif, png, tiff and svg. Some ...
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439 views

Evaluation an expression and rounding up to three decimals

I have an expression "5+50*3/20 + (19*2)/7" I need to round it up to 3 decimal places. The answer to this is 17.92857142857143. When I use the script below it is giving me 17.928. The answer should be ...
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804 views

how do I copy files like Microsofts “Robocopy” do in debian?

I've been trying to migrate small parts from my media/download center from windows to linux, before making the jump on my media center. Right now i have a Raspberry pi set up, with raspbian, where i ...
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250 views

How to get owner and full path of 50 large size file across all users?

Below command list top 50 files regardless of subfolders. $ls -lR /root/home | sort +4 -5nr | head -50 Current Result: -rw-r--r-- 1 john dpst 192954384 Nov 7 07:36 filenxx1.gz ...
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62 views

how do I remove ./ from the file name

How do I remove ./ from the file name ./script 1 when entering it as a command. I want to be able to enter the command just as script 1 for it to run?
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251 views

WMCTRL not working after starting xfce4-terminal

If I type these two commands in a terminal: xfce4-terminal --hide-menubar --hide-borders --hide-toolbars --title=dt wmctrl -r dt -e 0,10,10,720,720 I get the desired result (position and resize of ...
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606 views

How to find the process with maximum file descriptors?

What is wrong with this for loop? I am trying to find which process has the maximum number of file descriptors. The first command in the for loop ps aux | awk '{print $2}' prints out only the process ...
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145 views

Summing by common strings in different files

I have a file file1 with the amount of times a user shows up in the files, something like this: 4 userC 2 userA 1 userB and I have another file file2 with users and other info like: userC, degree2 ...
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1k views

bash script that reads user input and uses “cal” command to validate dates

I want to write a script that reads my input (for example if my script is called "check", then I would type "check 9 4 1993" and that input would go through the cal command and will check through the ...
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83 views

A script for making another script deal with all files in sequence?

I have found a nicely working script to convert pdf files into txt format, with ocr. But it converts only one pdf file each time. I need to mass-convert them. I have no knowledge of script ...