Questions about bash only, as opposed to other Bourne/POSIX shells. For all Bourne/POSIX-style shells, use the /shell tag instead.

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0
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0answers
13 views

Error opening terminal: Screen [migrated]

I just installed nano on my Nexus 9, which is rooted. However, when I try to run nano, it says "Error opening terminal: screen." bash-3.2# nano Error opening terminal: screen. Any help would be ...
7
votes
2answers
213 views

Shell script not able to awk created file

I'm trying to create some simple pass/fail test scripts, but I am having some challenges as outlined below. My intent is to get the full results of a command (such as ping) into a results.txt file to ...
0
votes
2answers
50 views

Combining two bash script and using a menu

I have two scripts, one that is used on a folder with csv files and another on a folder with .tar.gz files. In the second script, I first unzip the files before doing anything with them. Now I want to ...
3
votes
1answer
52 views

What is the difference between letting nohup append to 'nohup.out' and explicitly redirecting it to a file?

Consider the following scenario: tail.sh: #!/bin/bash tail -f test.txt invoke.sh: #!/bin/bash nohup ./tail.sh & invoke_explicitredirect.sh: #!/bin/bash nohup ./tail.sh > out.log & ...
1
vote
1answer
37 views

Echo newline with quotes [duplicate]

For: $hello="hello > world" Why does echo not print the newline for: echo -e $hello But if I put $hello in quotes it does. $ echo "$hello" hello world Is this because of ANSI-C Quoting? ...
2
votes
2answers
26 views

Current disk load

I'm using iostat to get the current disk load each second with iostat -dx 1 (specially, %util column). However, I'd like to put this in a bash script and control the interval with the watch command ...
2
votes
1answer
47 views

Concatenate and pass as parameter, bash

Need some help with removing default gateway. For example, there is an IP 192.168.4.15 with default gateway 192.168.4.14. I connect to WLAN with gw 10.0.0.1 and after that I would like do remove ...
2
votes
0answers
30 views

What are the benefits of using Tmux at all times? [closed]

I have been using the terminal for all of my local work, and have only been using tmux when I am ssh'd onto another machine and want to make sure I don't lose work if the connection closes. A software ...
0
votes
1answer
34 views

using CURL to transmit binary data over POST parameter

How can i use CURL to send binary data through a specific post parameter? E.g in: curl 'http://www.example.com' -H 'hi:hi' --data ...
-1
votes
1answer
29 views

Count values in first column where second column occurrences are the same in UNIX

I have to count values in first column of a file for which the second column occurrences are the same , using Unix. 12,abn 23,abn 45,hh 52,hh 89,mm 89,mm My output should be something like ...
2
votes
1answer
113 views

How to remove a filename from bash completion, based on its suffix?

Apologies if this is a duplicate, but I'm (unsuccessfully) trying to edit the bash completion options for vim. Specifically, when editing a LaTeX document, there are lots of supplementary files which ...
4
votes
2answers
85 views

Share environment variables between bash and fish

bash and fish scripts are not compatible, but I would like to have a file that defines some some environment variables to be initialized by both bash and fish. My proposed solution is defining a ...
1
vote
2answers
39 views

Checking URLs for HTTP code 200

I have a text file containing a list of URLs like this: http://somesite.com/some-article/ https://anothersite.fr/somepage.php?page=something What I'd like to do is check which URLs return HTTP code ...
1
vote
0answers
31 views

Career path with unix [closed]

I might get a -ve point hit for this one but i really need your opinion! I am a IT professional for about 4 years now (Support/application domain) with no as such expertise in one domain because i ...
2
votes
1answer
37 views

Input separator of the `read` builtin in Bash

Given such situation: echo "Please enter your name" read name # user enters: john smith echo $name # prints: john What could cause read to read only the first word of the input? Is there a ...
1
vote
3answers
34 views

the “done” message after a &-command is not displayed right away, but after a user action. Why?

I do a sleep 3 & and the "done" message is displayed as part of the ps command, not right on the console. It doesn't have to be ps. Any command after the sleep is done will have an extra line at ...
3
votes
1answer
32 views

Searching through C++ STL man pages without having to add “std::” every time

I have installed libstdc++6-4.7-doc on a machine with Ubuntu, so I could look up for things like std::pair from the command line. Is there a way to search for the same std:: entries without ...
0
votes
0answers
18 views

Makefile not prompting compiler to use optimization flag [migrated]

I have a simple makefile that I am using in bash to compile a C++ program and its associated .h files, not every .h file has a .cpp file associated with it. I wrote a makefile where each dependency ...
0
votes
1answer
31 views

Ugly bash function to send commands and “say” anything in screen over ssh. Is there a better way?

I’m working on a function this works but it is ugly. One thing that could be changed is being able to know the name of the screen. Using screen -dms minecraft java ….jar now starts a screen session ...
3
votes
2answers
78 views

Combining bash % with xargs %

This article says you can use a % syntax to remove file extensions: $ s=a/b.mkv $ echo ${s%.*} a/b How do you combine the % syntax with the % in xargs to achieve the desired result for a set of ...
2
votes
1answer
30 views

basename doesn't work as expected

How do I make ".mkv" disappear in the target filename? $ echo a/b.mkv | xargs -I % echo ffmpeg -i "%" $(basename "%" ".mkv").mp4 ffmpeg -i a/b.mkv a/b.mkv.mp4
2
votes
1answer
70 views

how handle a path ($1)

I've: /home/wms/mp3/ and /home/wms/tmp/ Inside ~/tmp my script: #!/bin/bash br=64 for a in "$1"*.mp3 ; do ffmpeg -i "$a" -ar 44100 -ab $br "$br""_tmp/${a%.*} ["$br"].mp3" ; done I do: ...
2
votes
1answer
87 views

Is there a difference between “gain root privileges” and “execute any command”?

I recently opened my sudoers file and noticed the following: # Members of the admin group may gain root privileges %admin ALL=(ALL) ALL # Allow members of group sudo to execute any command %sudo ...
3
votes
2answers
58 views

Append unix timestamp to files with space using a script

This script works fine for all files recursively as well but it does not name files that has space in between. For example it throws error for the files "this is a test.txt" or "test file.txt" Any ...
3
votes
2answers
62 views

bash add path to handle some files

inside ~/mp3 I've some mp3 files. My script: #!/bin/bash br=80 for a in $1*.{wav,mp3} ; do ffmpeg -i "$a" -ar 44100 -ab $br "$br""_tmp/${a%.*} ["$br"].mp3" ; with $1 add the path: myscript.sh ...
1
vote
4answers
78 views

Executing a command within `if` statement and on success perform further steps

I was trying to execute a program which will create a directory on the basis of a complete path provided to it from the prompt and, if the directory already exists it will return an error (for ...
-2
votes
1answer
34 views

bash for loop to run ruby scripts

I'm trying to run several ruby scripts from the command line. Here is my code so far: for i in {1..59}; do $("ruby sample$i.rb"); sleep 10; done The purpose is to test all these scripts quickly, ...
1
vote
1answer
58 views

How to permanently enable scl CentOS 6.4?

I installed a newer version of devtoolset (1.1) and was wondering how I would go about permanently setting these to be default. Right now, when I ssh into my server running CentOS, I have to run this ...
3
votes
4answers
118 views

How to swap entire html blocks in multiple files with sed

I have tons of html pages with a simlar content as follows: <div class="wrapper"> <div class="aaa"> ...lot of html1 here like div's/spans etc.. </div> <!-- end aaa --> ...
0
votes
1answer
34 views

kill parent and child because endless loop

I have a process run by cron every hour. Such process calls another one (not sourced), ie: ./childProc.sh (Not sure if this detail is important) Because of an endless loop in child process (which ...
2
votes
1answer
73 views

Is replacing a particular line in a file through a bash script possible in VIM or EX?

I would like to modify a particular line, say line 5, in a file by using the EOEX construct how can I achieve my aim? The code snippet that I use to achieve my purpose is as follows: #!/bin/bash ...
1
vote
2answers
47 views

Replace user shell from dash to bash [duplicate]

Everytime I use my terminal, I am always put into the dash shell instead of bash. Is there any way to change this even just for my user only? Tried apt-alternatives but setting the default shell can't ...
5
votes
2answers
188 views

Bash limiting precision of floating point variables

In Ubuntu 14.04.1 LTS 64-bit bash I am declearing floating point variables by multiplying floating point bash variables in bc with scale set to 3; however, I cannot get the number of digits after the ...
0
votes
2answers
55 views

Bash Script Parsing Argument not working correctly

i have the following bash script (taken from FFmpeg) #!/bin/bash ################################################################################ # # Script name: MultiMedia Concat Script (mmcat) # ...
2
votes
2answers
31 views

Bash globs as non-file arguments. Example: apt-get remove pkg-*

I know * and other glob patterns are transformed into words by pathname expansion, based on the current working directory. Hovever, some commands seem to use them for non file arguments. For example, ...
2
votes
1answer
45 views

Bash update list of running jobs with ps

I need to run in parallel a set of computationally intensive tasks. What I was trying to do is to maintain a list of pids corresponding to the running jobs and update the list of running jobs with ps ...
2
votes
2answers
53 views

Use config file for my shell script

I need to create a config file for my own script: here an example: script: #!/bin/bash source /home/myuser/test/config echo "Name=$nam" >&2 echo "Surname=$sur" >&2 Content of ...
-1
votes
2answers
15 views

OSX bash. grep for string “--version=”

How can I search for string --version= using grep in OSX bash? When I try something like this: grep -rI --exclude-dir=out "--version=" . I get grep: option `--version' doesn't allow an argument ...
3
votes
1answer
39 views

Shell expansion and positional parameters

I want to make an script equivalent to zgrep or bzgrep, but using tar. I made two very similar attempts and I would like to know if there is a better one and if they could be improved or they are ...
0
votes
0answers
25 views

run -i vs run -it?

I am using boot2docker on windows. I tried the following commands docker run -i centos /bin/bash docker run -it centos /bin/bash Both provides same kind of execution. I read -i is interactive ...
2
votes
2answers
78 views

Is there a reason to quote the exit status $? variable?

I was looking at Google's style guides for their bash scripts, and saw that they quote the exit status variable $? here. if [[ "$?" -ne 0 ]]; then error_message fi I thought return values are ...
2
votes
1answer
49 views

How to count the number of occurrences of a number larger than x, from every column?

I'm trying to figure out how to count the number of occurrences of values that are greater than some number (i.e. 0.1) in each column and then print that value out for each column. Here would be some ...
1
vote
2answers
46 views

Read Command : How to verify user has typed something

I am a beginner in Bash so please bear with me. I'm trying to create an if else statement to verify that the user has entered something. If they have it should run through the commands, and if not i ...
1
vote
1answer
43 views

let script find path of itself

I want to have a bash-script discover its own path. The background is that I have a script called process_scanned_text.sh, which itself uses the script curves. I put curves in the same directory as ...
2
votes
3answers
66 views

Execute command within variable

I'm trying to execute a command, stored within a variable: cmd="grep -i \"word1\" filename | grep -i \"word2\"" eval $cmd But when I execute the script I get the errors: grep: |: No such file or ...
3
votes
2answers
27 views

How to find a file with partially specified path?

I am trying to find all my .txt and .csv files in my backup (Apple's time machine). The structure of the backup directories is like this: /machine name/date/Macintosh HD/ The above contains all ...
3
votes
2answers
72 views

forward function and variables into sudo su - <user> <<EOF

I have declared functions and variables in bash/ksh and I need to forward them into sudo su - {user} << EOF: #!/bin/bash log_f() { echo "LOG line: $@" } extVAR="yourName" sudo su - ...
0
votes
1answer
25 views

Why doesn't this tee with process substitution produce the 1st and chosen lines? [duplicate]

What I want is printing the output the first line ( table head ) of ps aux and the grep result. After search, I come up with following. ps aux | tee >(head -1 > /dev/tty) | grep mongo But I ...
1
vote
3answers
64 views

looping a command without waiting for the first run

I want a better way to do this, mostly for command line use: while sleep 60; do mysql -e 'show processlist'; done This is better than: while mysql -e 'show processlist'; do sleep 60; done ...
1
vote
2answers
63 views

How does bash's arithmetic work?

read num1 2 read num2 5 echo "$((num1+num2))" 7 echo "$(($num1+$num2))" 7 I referred this. I don't understand how the above both expressions yields same result? Please explain. echo ...