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

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0
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1answer
44 views

Debugging with shell programming and cpp files?

I am having trouble understanding how my code is working. I am new to this project and never learned unix before. My coworker quickly showed me how to run the program but didn't explain how it worked ...
1
vote
0answers
18 views

Take the unknown contents of variable as literal in sed [duplicate]

I have two files: a.patterns contains patterns in a one per line way "`" "^" "<" "<(" "<)" "<[" "=" ">" "_;|^+*+?@" and b.data contains comma separated values. 1,1,0,"*",1 ...
1
vote
2answers
84 views

How do I expect 'echo -e “? \c”'?

I'm an absolute newbie to the UNIX world and have been asked to write a script that interacts with another one - but I'm stuck. The script that I interact with echos the following and I need to send a ...
-2
votes
4answers
57 views

How to ignore the lines starts with # using grep / awk

cat /etc/oratab #test1:/opt/oracle/app/oracle/product/11.2.0.4:N +ASM2:/grid/oracle/app/oracle/product/11.2.0.4:N # line added by Agent test2:/opt/oracle/app/oracle/product/11.2.0.4:N ...
1
vote
1answer
75 views

How to run “&” operation sequentially

From my script I am running following commands: SCRIPT_1="ksh -x script1.sh & ksh -x script2.sh"; SCRIPT_2="ksh -x script3.sh & ksh -x script4.sh"; eval $SCRIPT_1; sleep 20s; eval ...
1
vote
1answer
41 views

using bash script to sort text in a file

I would like to sort the output of multipath -ll into a csv type of file using bash script. For example # multipath -ll would give the following output 360060e80056fc30000006fc30000513c dm-41 ...
2
votes
0answers
37 views

“login -qf” as root results in “Login incorrect” error

I'm trying to install pow on an OS X machine.* Some of pow's components have to run as root, so part of the setup process involves running an installation script with sudo. The problem is, this setup ...
3
votes
1answer
51 views

Problem with passing parameters containing spaces and wild card characters

I have a problem passing parameters if the parameters may contain wildcards and/or spaces, if those parameters are optional. Since this sounds pretty abstract, let's have a small example: The ...
0
votes
1answer
39 views

How to name a directory by combining two variables?

I want to name a directory by combining the the values of two variables. eg: dirname="$var1" '.' "$var2".
6
votes
3answers
210 views

sed with multiple expression for in-place arguement

I am trying to replace multiple words in file by using sed -i #expression1 #expression2 file Something 123 item1 Something 456 item2 Something 768 item3 Something 353 item4 Output (Desired) ...
2
votes
2answers
72 views

Using Diff on a specific column in a file

Will it be possible to use diff on a specific columns in a file? file1 Something 123 item1 Something 456 item2 Something 768 item3 Something 353 item4 file2 Another 123 stuff1 Another 193 ...
3
votes
4answers
68 views

Inner loop conditions shall depend on outer loop run

How can I build an inner loop such that the loop condition depends on the outer loop run? My very situation does probably not matter for the code I am looking for, but here it is: I have a crawler ...
2
votes
2answers
76 views

What is the purpose of using shift in bash scripts?

I have came across this script: #! /bin/bash ...
3
votes
1answer
67 views

sed repeating the last line in the stream

I have code in a script similar to this... smbconffile="/etc/samba/smb.conf" sed -i 's/.*[\[CMI\]]/\[CMI\$\]/' $smbconffile && echo "Success" || "Failed" sed -i 's/.*[\[LOCAL\]]/\[LOCAL\$\]/' ...
2
votes
3answers
88 views

source /dev/stdin doesn't work as expected

Let's start with simple tests that work for me to check that source /dev/stdin can be used at all. # echo -ne 'echo a\necho b\n' | source /dev/stdin a b Now I would like to source an actual ...
0
votes
1answer
105 views

Start script on boot up?

I want to run a script when the system starts. The script is: #!/bin/bash gnome-terminal --tab -t "MyPC" -e "sh -c 'nohup firefox & nohup gedit & bash'" --tab -t "MYPC2" -e "sh -c 'ls -al;ls; ...
1
vote
0answers
28 views

POSIX compliant shell script not portable because of the tools used inside [closed]

I've written a script which runs in a strictly POSIX compliant shell without trouble on my machine but a buddy of mine couldn't execute it. It seems as if his machine has different versions of tools ...
1
vote
1answer
25 views

xmessage in a script freezes

I use the following script called from a udev rule in order to automate backup: #!/bin/bash export DISPLAY=:0 export XAUTHORITY=/home/gauthier/.Xauthority # ... other things like offering abort, ...
0
votes
1answer
66 views

bash: What is the difference between these two script variants?

(Note: Both of these examples may require GNU or BSD find and may not work as-is with the POSIX "edition" of find). Both of the scriptlets below must be understood as excerpts from way more complex ...
1
vote
0answers
19 views

run a certain file (e.g. a .py) when a certain image, .wav or excel file get opened [duplicate]

Recently, me and my friend have purchased a Palm Vein Scanner. the goal was using it in a mini-project as a new door lock system. we are connecting it to a Raspberry Pi to run the software on it. ...
1
vote
1answer
29 views

Shutter Script(s)

When i play some games with wine , i must not change the window , because of that , the game crash or that window are fill of black. im using xfce4 desktop , when i press "PrintScreen" key from ...
3
votes
3answers
502 views

Replace %20 with a space in filenames? [duplicate]

I have a list of files that are using %20 to indicate a space in their names. I'm currently trying to do the following to change them all from %20 to a space " ". for x in *.txt do mv $x $(echo $x ...
1
vote
1answer
74 views

Number of packets sent and received on an interface

I'm interested in creating a script which prints total number of received packets and sent packets on an interface. The output should be like: interface TX: number RX: number Can anyone help me ...
-1
votes
2answers
156 views

delete files having a certain pattern in their names

I want to delete all files that have two numbers and a dot in beginning of their names for example: 01. abc 02. xyz
-3
votes
1answer
60 views

If statement to compare files

I need to make an if statement that: compares the files finds the differences between them gets a word count of both files pastes the information from one file to another But I do not know if I'm ...
0
votes
1answer
34 views

Bash Script Not changing Directory

I have a small script I am working on where I need to read in a few Strings: #!/bin/bash echo "Enter SUID: " read $uid echo "Enter Tag Number: " read $dicomTag dicomDump() { arg1=$1 ...
2
votes
3answers
164 views

Find files newer than a day and copy

I am working on a script that will copy ONLY files that have been created within the last day off to another folder. The issue I am having is the script I have copies all of the files in the source ...
6
votes
1answer
184 views

Is it better to use $(pwd) or $PWD?

I encountered BASEDIR=$(pwd) in a script. Are there any advantages or disadvantages over using BASEDIR="$PWD", other than maybe, that $PWD could be overwritten?
1
vote
3answers
83 views

Calculate and round numbers up in bash

I'm struggling with a slight variation on: How to calculate by taking first field and How to round floating point numbers in shell? I have a file that looks like (space between columns): 1533 ...
4
votes
1answer
104 views

cmd2 `cmd1` vs cmd1 | xargs cmd2

I'm trying to find a file with find and then pass the found path to sqlite3. I'm only dropped into the sqlite> prompt if my command is of the form: sqlite3 `find . -type f -iname "*.db" | head ...
3
votes
1answer
203 views

bash: non blocking read inside a loop

I have a following small bash script var=a while true : do echo $var sleep 0.5 read -n 1 -s var done It just prints the character entered by the user and waits for the next input. ...
2
votes
3answers
65 views

Is there a simple way to find out the last line executed in a bash script?

In answering this question please bear in mind that I am a beginner and a bit out of my depth. I'm running a bash script which contains a for loop which will run thousands of times. Somewhere in this ...
2
votes
2answers
107 views

How to retroactively make a script run as root?

I'm writing a shell script, that needs to be run with root privileges. I can check if a user has root privileges with sudo -nv || echo "no sudo", but that doesn't help me, if his credentials are ...
0
votes
2answers
54 views

Command to see if a word is in a list of files and output how many files it is in

There is a similar question to mine already but mine has a slight difference. I want to see how many files contain each word. When a file has a word then it increments the counter and then continues ...
0
votes
1answer
35 views

Syntax of process substitution

I am really having some trouble understanding pipeline substitution. I have a program that I run with the make command that writes to stdout. What I want to be able to do is parse through the output ...
4
votes
2answers
51 views

Is there a way to have a function in my bash script auto run on any command error?

I'm writing a shell script that needs to do a bunch of commands and every command depends on every previous command. If any command fails the entire script should fail and I call an exit function. I ...
1
vote
1answer
131 views

Storing longer text output in memory in shell variables vs Writing to disk

I have the below call to db2 command line tool inside a loop which runs 100k iterations. (the db2 output is 5 rows of 20 chars approx per each call, total of approx 100k calls. The input to SP is ...
23
votes
2answers
2k views

Why does ( echo “”; exit 1) not exit the script?

I have a script, that does not exit when I want it to. An example script with the same error is: #!/bin/bash function bla() { return 1 } bla || ( echo '1' ; exit 1 ) echo '2' I would assume ...
0
votes
2answers
51 views

Using variable with awk -v in a shell script

I am modifying/re-writing some of the scripts written by former employees of my company and in one of the shell scripts I found the following line. b=`benchmark=30;grep "Waiting for timer" wk.txt | ...
1
vote
1answer
41 views

How to continue a script after X has been closed?

I recently installed RetroPie on my Raspberry Pi and I'm trying to find a way to (once I'm in LXDE) run a shell script that kills X and then starts EmulationStation. I can kill X with pkill x but then ...
0
votes
2answers
47 views

output a variable value using echo command [duplicate]

I want to output number of lines in text file.So I am using echo command but I am getting filename along with number of lines when I run the following code: echo "$page" > t total="$(wc -l t)" ...
2
votes
2answers
64 views

Check files for conventions

I need a script that checks and lists all text files for project conventions. With conventions I mean for example: UTF-8 encoding No trailing white spaces Newline at the end of file No not-ascii ...
0
votes
1answer
29 views

Count number of times each line repeats itself, In case Insensitive manner

I have a file like a A b c I want to print number of times each line repeats it self in a case insensitive manner. I found below command to be useful: tr A-Z a-z | uniq -c | sed -e 's/^ *//' -e ...
2
votes
3answers
242 views

find, xargs and mv: renaming files with double-quotes, expansion and bash precedence issue

Ok, I'm simply trying to strip out double-quotes in my filenames. Here's the command I came up with (bash). $ find . -iname "*\"*" -print0 | xargs -0 -I {} mv {} {} | tr -d \" The problem is the ...
-2
votes
1answer
56 views

Sorting a file based on second column in a Tab Spaced file [closed]

This may be a duplicate, But I have a Tab separated file and I need to sort the file based on second column which are float values. sort -s -k2,2gr -t$'\t' The code states it is to sort based on ...
1
vote
3answers
73 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 ...
1
vote
6answers
403 views

Print numbers from 1-50

x=1 while [ $x -le 50 ] do echo $x $x=(($x + 1)) done I have wrote the above code. What seems to be a easy task in many programming languages is giving this error for me. solution.sh: line ...
3
votes
2answers
51 views

Script to replace all symbolic links to a target to point to another target (in the same directory)

Given the following contrived example: $ mkdir -p a/b && touch a/b/original-target && touch a/b/new-target $ mkdir -p c1/c2 && cd c1/c2 && ln -s ...
2
votes
1answer
72 views

Bash variable ${0##*/}

I am trying to understand the variable ${0##*/} that I encountered in a bash script. I understand that $0 contains the name, or the path, of the script, then ## works as in ${parameter##pattern} ...
2
votes
3answers
145 views

Command for finding users who are not logged in

Is there any command that can find the number of users that are not logged into the system ? I am trying to write a shell script that counts the number of users who are logged in and number of users ...