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

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2
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7answers
5k views

Hiding Password in Shell Scripts

How can I hide a password in shell scripts? There are a number of scripts that are accessing database. If we open the script others also aware the username and password. So if anyone knows how to hide ...
0
votes
1answer
24 views

move files with special characters to new directory

I'm trying to write a loop for a script that checks a specific directory for any special characters and moves those files to a specific directory (except spaces and hyphens - those are simply replaced ...
66
votes
1answer
7k views

Why does the following script delete itself?

If you create an executable file with the following contents, and run it, it will delete itself. How does this work? #!/bin/rm
45
votes
11answers
32k views

Correct locking in shell scripts?

Sometimes you have to make sure that only one instance of a shell script is running at the same time. For example a cron job which is executed via crond that does not provide locking on its own (e.g. ...
2
votes
2answers
33 views

Send command output to screen and syslog

I'm trying to send the output of a command to our syslog and this is what I have so far. #!/bin/bash log() { logger -s -t $(basename $0) "$@" } /bin/echo "test" 2>&1 | (log) and this ...
0
votes
4answers
48 views

How to remove duplicate rows from a file?

File, TABLE1 ------- 1234 TABLE1 ------- 9555 TABLE1 ------- 87676 TABLE1 ------- 2344 I want the output like TABLE1 ------- 1234 9555 87676 2344
2
votes
0answers
30 views

Memoizing/caching command line output

I have a bash script I use to run a few python and C++ programs in a sequence. Each program takes in some input parameters which I define in the bash script. So as an example I run the program like ...
13
votes
5answers
1k views

Compress a large number of large files fast

I have about 200 GB of log data generated daily, distributed among about 150 different log files. I have a script that moves the files to a temporary location and does a tar-bz2 on the temporary ...
1
vote
2answers
766 views

Find last line of a file for matching string?

I want a loop that runs infinitely over a file but always checks the last line to see if it contains the matching string if it does then echo that line and keep the loop running. What I have right now ...
1
vote
2answers
51 views

How to modify (not add to) a number variable?

Suppose that a=$((1)) How can I change the value of a from 1 to 01? I just want to insert the 0 before the current value of a and rewrite it. a=$((01)) would not be a solution in this case because ...
-4
votes
1answer
28 views

Unpack a shell archive (.shar file)

I have a shell script. How can i remove anything before # this line Everything before the # should be deleted. The script is too long to delete it manually. How can I do that automatically? ...
9
votes
2answers
146 views

Shell Syntax: How to correctly use \ to break lines? [duplicate]

I used to believe that the appropriate way of breaking the lines in a list is command1 && \ command2 It turned out that it isn't so , one doesn't need \ $ [ $(id -u) -eq 1000 ] ...
2
votes
1answer
31 views

If there are more than x number of pipes in a csv line, then delete the 2nd instance

I have a csv file which is supposed to contain 4 columns of data which include a product number, a title, a url and a price. Each column is separated by a | delimiter (this has to be maintained, there ...
0
votes
1answer
53 views

How to pass a parameter with space in nohup? [duplicate]

I have script to run a jar, like shown below. user="Tim Tom"; jarfile=./app.jar SC_CD="java -jar -Xms512m -Xmx2048m -DUSER='$user' $jarfile" nohup $SC_CD And im geeting error message as Error: ...
1
vote
2answers
44 views

How to rename certain directories if the parent has a particular name?

I have to do some global renaming in an Eclipse plugin project, although the fact that the code is Java and it's an Eclipse plugin is irrelevant. Basically, the steps I need to perform are the ...
-7
votes
0answers
37 views

Unix Script to read log file [on hold]

I've a requirement to read recent five log files out of 100. Each log file contains pattern like below: Log Pattern 04/30/2016 01:01:26.073 INFO => T:1 ########### big data retrieve tier 2 call ...
9
votes
5answers
8k views

How can I print only certain commands from a bash script as they are run?

I have a bash script with various if statements based on command line arguments I pass in when calling it. Having some kind of output as to what commands are being run is helpful to confirm the flow ...
0
votes
1answer
35 views

How to maintain only four lines in my file in shell scripting?

Input file: 01.05.2016 87893938 02.05.2016 35435345 03.05.2016 35435345 04.05.2016 12345678 I want to keep only four lines in my file. that means if date 05.05.2016 6905698 is inserted then ...
1
vote
2answers
72 views

sh AND and OR in one command

Trying to check for 3 conditions in one line of code, but I'm stuck. Essentially, I need to code for the following: IF string1 is not equal to string2 AND string3 is not equal to ...
0
votes
2answers
31 views

Add newline character to file

Hi Guys i need to change the below single line string using a shell script {1:F01NESWSZM0AXXX1111111111} {2:I940BBRUBEBBXXXXN} {3:{108:400MSOG161200FRO}} {4: :20:400MSOG161200FRO :25:1xxxxxxxx65 ...
2
votes
1answer
65 views

Cannot mv to a subdirectory of itself

I am running this simple script and I am trying to create a cron job so that the file gets copied to my thumbdrive (with the new name) sudo cp /home/pi/NewLog.log /media/usb sleep 20 cd ...
2
votes
1answer
28 views

Why does this script not accept two arguments?

Code #!/bin/sh # http://tex.stackexchange.com/a/20886/13173 # http://unix.stackexchange.com/a/280830/16920 # $Id: pdf2eps,v 0.01 2005/10/28 00:55:46 Herbert Voss Exp $ # Convert PDF to encapsulated ...
1
vote
1answer
1k views

Cannot add startup service to openWRT from init.d

I have openWrt installed on a TP-Link TL-WA901N/ND v3. I don't have luci package installed because I don't have enough space, so I can only do thing via cli. What I'm trying to achieve is to create a ...
0
votes
3answers
37 views

Issue with the shell script after storing the directory in a variable

FTP is connecting to the server but i am getting an error - Enter if the env is dev or test or prod: test Please enter the id no : xxxxxxx Connected to xxxx 220 (vsFTPd 2.2.2) 331 Please specify the ...
0
votes
1answer
14 views

custom shutdown script in rc6.d does not seem to be working.

I'm working with a software application that's a bit touchy so I wan't to shut the software down automatically on reboot or shutdown. I have created a script an placed it in /etc/init.d/ with a ...
-3
votes
0answers
26 views

Regarding shell script [on hold]

I have 3 servers, one is the app server and the other two are database servers. Following are the IP addresses of my servers: App server: 192.168.1.1 DB-server-1: 192.168.1.2 DB-server-2: ...
0
votes
2answers
30 views

.sh query - running a ssh task

This is on a macintosh but it's still unix command. I am running some computers on a network that have file sharing turned off because of security so the only way to connect is via ssh. I need to ...
9
votes
3answers
8k views

whiptail or dialog

I am going to create script which will use user input, so I decided to use whiptail, but little bit confuse that which one is portable and will work in ubuntu 10.x and higher and CentOs5.x and higher. ...
0
votes
1answer
37 views

Script too slow ? Any particular reason?

I have a script which does hexdump along with pipeline commands and finally I am redirecting it to a file. Now I am logging data from the serial port of my Raspberry Pi. I also call a python ...
79
votes
2answers
3k views

Security implications of forgetting to quote a variable in bash/POSIX shells

If you've been following unix.stackexchange.com for a while, you should hopefully know by now that leaving a variable unquoted in list context (as in echo $var) in Bourne/POSIX shells (zsh being the ...
0
votes
1answer
3k views

LFTP mirror upload only non existing files to remote directory

Every 5 minutes some new files are downloaded via lftp to a local directory. I need to upload to another ftp only the non existing files. My script so far is: #! /bin/bash today=$(date +%Y%m%d) ...
1
vote
1answer
25 views

how to inject keystrokes in a program like Safari from a bash script?

I am trying to automate some keypresses every few minutes. The exact timing is still undetermined. But basically I want to capture a live chat dialogue. I'm sure I could do this more elegantly. I ...
1
vote
1answer
41 views

Printing the file with number of hardlinks

I can print the number of hardlinks to files in directory by using find . type f -printf "%f %n\n" but this will also print the hardlink not only original files: Example: file1 is an original ...
21
votes
6answers
47k views

#!/bin/bash - no such file or directory

I've created a bash script but when I try to execute it, I get #!/bin/bash no such file or directory I need to run the command: bash script.sh for it to work. How can I fix this?
3
votes
3answers
101 views

Reverse sequence of a file with POSIX tools?

Is there any clean, clear-cut POSIX equivalent to tac? Readability as well as succinctness should both be considered.
0
votes
2answers
508 views

Unix Shell script to delete all traces of itself after execution through crontab

My Question has 2 parts. Help with both parts is greatly appreciated. GIVEN INFO: - Lets assume there are 2 Folders, Folder A and Folder B. - Folder A contains many files. - Folder B contains the ...
0
votes
3answers
46 views

sed substitution

I have a string as follows: /test/test/ 12 /test/test My goal is to turn it into: /test/est/ 12 /test/test This is the command: echo "$x" | sed 's@\(/*/\).@\1@g'" I am using at the moment but ...
3
votes
2answers
48 views

Accessing Google-translate via wget

I don't want to call the whole Firefox/Chrome/Opera... to find out the meaning of a word with the Google translate, so I decided to write a shell script which uses wget to get the content of ...
3
votes
3answers
82 views

How to prevent script from deleting itself

Hi I'm creating a recycle bin script with the command name 'safe_rm'. I was wondering, how can I prevent the script from deleting its own file. I believe the readlink command is one solution however ...
1
vote
1answer
31 views

Rc.local not running commands properly

I am running arch Linux and have used this rc-local service: [Unit] Description=/etc/rc.local compatibility [Service] Type=oneshot ExecStart=/etc/rc.local RemainAfterExit=yes [Install] ...
1
vote
0answers
25 views

Access to bash arrays in gnuplot [duplicate]

In a bash script I have several arrays which I need to access in a gnuplot code: #!/bin/bash ... # fill array a[*] and b[*] ... gnuplot <<EOF do for [j=0:10] { # access ${a[j]} and ${b[j]} } ...
-3
votes
1answer
59 views

Need help in a shell script

I need help with the below shell script. I have three environments: test, dev and prod. When the user enters test it should ftp to test host and ftp the file. Same in case of dev and prod. I have just ...
5
votes
2answers
464 views

Create symlink tree in existing directories

I carry all of my music around on a 1TB USB drive and have a udev rule to symlink it to $HOME/Music/ when I plug it in to one of my laptops, which it does. The issue I have is that this works fine ...
-6
votes
0answers
27 views

How to find Multiple strings present inside a file and send a automatic mail if not present [on hold]

I have a requirement like there are 9 strings i need to look for in two files(one has 4 and another has 5). My script should look into those files and notify me via mail if its not present. Hi, let ...
8
votes
3answers
12k views

Why is my variable local one 'while read' loop, but not in another seemingly similar loop?

Why do I get different values for $x from the snippets below? #!/bin/bash x=1 echo fred>junk ; while read var ; do x=55 ; done <junk echo x=$x # x=55 .. I'd expect this result x=1 cat ...
4
votes
2answers
60 views

Millisecond time in a shell script

How can someone print the entire time ie, for example 12:07:59:393(HH:MM:SS:milliseconds) in milliseconds. I found a lot of posts saying how to print Milliseconds along witht HHMMSS but I want to ...
4
votes
2answers
3k views

Testing a string containing only spaces (tabs, or “ ”)? [duplicate]

My code below doesn't work: stringZ=" " if [[ "$stringZ" == ^[[:blank:]][[:blank:]]*$ ]];then echo string is blank else echo string is not blank fi Result: string is not blank # wrong ...
0
votes
1answer
31 views

tar directories containing spaces [duplicate]

I want to archive my photos into tar archives. The directory containing photos has one dir per year and multiple dirs inside each year dir: Photos 2005 2006 Some dir with spaces ...
0
votes
0answers
26 views

Fixing Signal 13 Error on find

I have a situation where I'm trying to install softwares into my system. I'm using a fakeroot approach to install them in a separate directory where I'm listing all the files, directories and links ...
1
vote
0answers
12 views

Linux Mint Corners Musical Sequence Associative Array

I am writing a script which uses hot corners to play specific musical notes when hovering in corners, and depending on the musical sequence to execute a specific command. The script is called with ...