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

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2answers
139 views

How can I tell what device or file name I am redirecting to

From within a shell script (sh/bash), how can I tell what device or file name I am redirecting to? For example, I have a shell script named script.sh. I run the shell script and redirect STDOUT to a ...
1
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1answer
54 views

Automatically copy PDF.plugin to Chromium.app

I'm using Chromatic.app to update my Chromium.app recently. I'd like to use Chrome.app's PDF.plugin in Chromium.app. Therefore I need to copy PDF.plugin to the following directory: ...
3
votes
4answers
3k views

Replace all newlines to space except the last

How can I replace all newlines with space except the last newline. I can replace all newline to space using tr but how I can do it with some exceptions?
0
votes
1answer
2k views

shell unexpected end of file error

I had the below script working in a linux machine. page="$(curl http://www.google.com/| grep "title")" if [ -z "$page" ]; then echo "Empty page" else echo "Valid page" fi When am running in ...
0
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3answers
2k views

grep to extract substrings in a string

I have an output for a command as below. Heading1 I am one value. I am another value. I am third value. Heading2 I am some value. I am someother value. I am new value. Heading3 ...
1
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1answer
914 views

grep to extract a substring from a huge string

I am extracting certain information from a website using curl command. I need to extract a certain subsection of the string using grep command. For example, using curl command I am getting the HTML ...
5
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2answers
4k views

How to compose bash functions using pipes?

I have few functions defined in this fashion: function f { read and process $1 ... echo $result } I want to compose them together so that invocation would look like f | g | h. What idiom ...
2
votes
1answer
5k views

curl and grep commands output into a new variable

I am extracting information from a website. I designed the code in VBA and found that it is taking too long to execute. So, I have decided to rewrite the code in Unix script. I am extracting a page ...
1
vote
1answer
294 views

Editing the .profile file to access

I am trying to source my .profile file to easily access a directory of javatools. The bash code below seems like it should work but it does not. Any help troubleshooting this script would be very much ...
2
votes
2answers
221 views

How to add an audio file to a shell script

How can I add an audio file (OGG vorbis) into a shell script making the script as small as possible and at the same time being able to execute it on as most systems as possible? I want the audio file ...
0
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1answer
214 views

Bash script for copying text currently entered to prompt

I'm trying to minimize using of mouse. Copying text in terminal is the mostly inconvenient activity for mouse avoiding. Now, tmux helping me to obtain this purpose. However, I regularly needs to copy ...
8
votes
2answers
515 views

Cache all gpg subkey passwords at once? Prevent need for multiple gpg password entry?

Can I enter my gpg password just once and unlock all my sub keys (signing, decryption, authentication)? At the moment, I need to enter my gpg password three times (for signing, for decryption, for ...
2
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2answers
2k views

Do I need to encapsulate awk variables in quotes in order to sanitize them?

As per an answer on stackoverflow, it's my understanding that encapsulating bash variables in double-quotes is a fairly safe way of sanitizing user input. What about awk variables? For example, if ...
5
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2answers
2k views

Add thousands separator in a number

In python re.sub(r"(?<=.)(?=(?:...)+$)", ",", stroke ) To split a number by triplets, e.g.: echo 123456789 | python -c 'import sys;import re; print re.sub(r"(?<=.)(?=(?:...)+$)", ",", ...
1
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1answer
248 views

Bash Script which can direct stdin stream to program

I am trying to create a script capable of infinitely processing an incoming stream which is piped to it, and continuous producing an output stream which can be piped to something else something as ...
5
votes
2answers
166 views

run perl script with unknown perl location

I'm developing a perl script which expected to be downloaded by Mac users with a very small knowledge of shell, linux etc, let's say office managers and accountants. After the downloading the script ...
1
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1answer
157 views

Shell script to list locked packages in FreeBSD

I'm trying to make a oneliner to be able to list all locked (forbidden to upgrade) packages in FreeBSD. Normally, you issue this command: pkg info -ak It outputs list of all packages in system ...
2
votes
3answers
2k views

How to count specific strings in file?

Using hash table to count specific strings, and out put a result with time it repeat. File A AAA BBB CCC DDD BBB DDD AAA CCC BBB AAA BBB CCC BBB Result AAA 3 BBB 5 CCC 3 DDD 2
1
vote
1answer
2k views

Basename gives extra operand error

I 'm using the following script to merge few pcap files into one using mergecap command. But when I run it it gives me a 'basename: extra operand /mnt/md0/capture/DCN/dcn_2014_02_04_00_11_47_598.pcap' ...
-3
votes
1answer
109 views

why does the dollar sign cause this command to be executed?

test_script.sh: #!/bin/sh D1="$(dirname $0)" echo $D1 D0="(dirname $0)" echo $D0 What I type on the command line: $ ./test_script.sh Output: . (dirname ./test_script.sh) What significance ...
0
votes
1answer
717 views

Can I use an if statement to detect if bash and dash are being run interactively? [duplicate]

After looking around for a while I've found several good pages describing how to check and see if a bash script is running interactively and there seem to be several methods, but one of them that I ...
3
votes
1answer
398 views

BASH : Array as String Buffer

Instead of displaying (or writing) every result once generated, i designed an Array based Buffer to store data and write it whenever the line counter reaches a MAX value. Here is the script : ...
4
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3answers
825 views

“history” stops working when run inside bash script

I am writing a simple script to grep my bash history to find a particular string. On the command line, I can do the following, which works fine: history | grep git However, when I create a bash ...
1
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1answer
190 views

Is there a graphical shell or scripting environment for Linux?

I would like to draw my scripts and connect commands like blocks of functions (something similar to Yahoo Pipes). Does such an environment exist or do I have to develop it myself?
0
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2answers
3k views

How do I edit /etc/rc.local? [closed]

Im using Raspbian and trying to edit /etc/rc.local. When I run sudo nano etc/rc.local or just sudo nano rc.local it creates a new file. And anything I try to edit in leafpad won't save.
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1answer
1k views

Calling an email script from another script using ssmtp on ubuntu

I have an issue with a script, which works fine except that it only sends email when I run it directly from the shell but when called during crontab it doesn't send the emails. There are 2 scripts ...
2
votes
1answer
119 views

Can I apply `tmux` to a bash script?

Is it possible for me to use tmux to SSH into a Raspberry Pi, run a Bash script, and then leave the session (from my laptop), while the Raspberry Pi continues to run the script?
1
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5answers
600 views

Is there a way to make a Bash script enter a certain keystroke?

Is there any way to make a bash script enter a certain keystroke? What I'm trying to accomplish here is a script that will run Ctrl+B to exit tmux. EDIT: I see that several people are saying that ...
4
votes
1answer
2k views

How to strip color codes out of stdout and pipe to file and stdout

I have a program that uses printf with some tput mixed in it and I'd like to pipe the output to stdout as well as a file. I'd prefer to use sed since I don't want any unnecessary dependencies on my ...
4
votes
4answers
516 views

Keeping the number of files in the folder constant by deleting old files

I'm trying to create a script and run it in crontab every 5 min, so that the number of files in a folder always remain 50000. If there are more, I want the script to delete the old files. ...
1
vote
4answers
106 views

How to get started with bash? [closed]

I need a way to be able to run a script that will automate terminal commands, one after another. As I understand it, this is exactly what bash does. (Am I right, even on this count?) Where can I ...
0
votes
1answer
1k views

How I append the data of Multiple files into one file?

I want to append data of approx 500 files into one file and each of these files are located in their respective dirs. Also How i can verify the contents of merged file e.g How i verify that data ...
0
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2answers
245 views

How do I create a folder with a username and date as the folder name?

I need to write a backup script. I need to be able to run the script from any computer and have it pull the username and date as the directory name. Each computer has an admin account and a user ...
0
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1answer
76 views

How to measure rlogin time?

I need to monitor the time it takes to rlogin from one HP-UX machine to another. So I wrote this: #!/bin/sh result=`rlogin 10.10.10.1 << EOF exit EOF` result2=`{ time $result >/dev/null; } ...
2
votes
1answer
207 views

indirect variable expansion in POSIX as done in bash? [closed]

Is it possible, or is there some elegant hack to do indirect variable expansion in POSIX as can be done in Bash? For context, I'm trying to do the following: for key in ${!map_*} do # do ...
10
votes
7answers
5k views

bash: test if $WORD is in set

I am looking for a construct in bash, to decide if a variable $WORD is one of defined words. I need something like this: if "$WORD" in dog cat horse ; then echo yes else echo no fi does ...
3
votes
1answer
106 views

Count and merge consecutive patterns

I'm searching for a short snippet to find, count and merge consecutive duplicates using standard tools or a common scripting language. Say our input is: 1 2 2 2 7 22 a b b c c c c c d dd 2 2 c c ...
6
votes
2answers
6k views

Associative Arrays in Shell Scripts

I saw a trick for implementing associative arrays in a shell script. For example print array["apples"] could be scripted as echo \$array$key where key=apples. However, there was no mention of how to ...
2
votes
2answers
607 views

How do I check that a filename conforms to a pattern?

I'm tasked with writing a shell script which checks that a filename conforms to a specific pattern and I'm not sure how to go about it. The filename should follow a pattern which looks like: ...
7
votes
2answers
2k views

Local variables in zsh: what is the equivalent of bash's “export -n” in zsh

I'm trying to contain the scope of a variable to a shell, and not have children see it, in zsh. For example, I type this in .zshrc: GREP_OPTIONS=--color=always But if I run a shell script with the ...
0
votes
2answers
914 views

bc removes decimal point

This is related to Shell script too slow for output to Conky This code is nearly perfect: stdbuf -oL jack_cpu_load \ | grep --line-buffered "jack DSP load" \ | stdbuf -oL cut -d' ' -f4 \ ...
0
votes
2answers
2k views

Using AWK to delete line and output result

I have a text file and manage to find the line through output comparison. With the book title and author name. awk -F ':' '/KungFu Feet|Chuck Norris/' test.txt Kungfu Feet:Chuck Norris:12:1:1 Is ...
2
votes
3answers
4k views

Backup files with tar command and progress bar? [duplicate]

Can I see a progress bar or something not only ust the terminal screen output while backing up? Here is my shell script that I used backup with tar command: # !/bin/bash DATEJOUR=$(date ...
3
votes
3answers
370 views

Shell script too slow for output to Conky

I want the output of stdbuf -i0 -o0 -e0 jack_cpu_load | sed -n 's/[A-Za-z]*//g;s/ //g;s/.\{4\}$//;9,$p' to be displayed in Conky but, I suspect, Conky is starting the script with every refresh and ...
1
vote
1answer
403 views

how to send keyboard signal using a shell script

I have an application in graphical interface that when I run it, it's not opened in full screen mode, but when I use the keyboard shortcut Alt+Ctrl+M , it becomes fullscreen, I want to change the ...
2
votes
1answer
64 views

Pipe output of jack_cpu_load through sed

In the shell, when I pipe jack_cpu_load through sed, or cut, no matter what options I use it stops printing just before the lines I want to see. jack_cpu_load | sed -n 8p will print: Jack: ...
1
vote
1answer
153 views

Unknown syntax in /etc/rc.d/init.d/functions

Looking at the file /etc/rc.d/init.d/functions, I can see the following is declaring a number of variables as local variables. However, why are the variables killlevel and pid_file have an equal sign ...
4
votes
2answers
1k views

Find files newer than another file within each subdirectory

I have a folder structure like this /Class/Student/Unit/files Each Unit folder contains a file MarkSheet* that I update when I mark a students work. I need a script that tests if the student has ...
3
votes
5answers
319 views

Join two files, matching on a column, with repetitions

How can I get two files A and B, and out put a result like this: File A: 001 Apple, CA 020 Banana, CN 023 Apple, LA 045 Orange, TT 101 Orange, OS 200 Kiwi, AA File B: 01-Dec-2013 01.664 001 ...
-2
votes
1answer
390 views

automatic capturing top output by cronjob CENTOS 6.5 x86_64

I have this command: top -n 14400 -a -b -d 1 > /toplogfile.txt I want to make a script which is run by cron every day to capture top output, and if it is possible gzip the output file after the ...