Questions specific to GNU’s Bourne Again SHell, as opposed to other Bourne/POSIX shells. For questions about Unix shells in general, use the /shell tag instead.

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4
votes
3answers
549 views

processing command output line by line, without mixing standard input

So, I have a problem very similar to Bash: How to read one line at a time from output of a command?, I am doing: while read path; do mplayer $path; done < <(find-me-random-mp3s) or find-me-...
3
votes
2answers
6k views

Using a variable in a regex

How can I use a variable string in a regular expressions while read line do if [[ line =~ *"$key"* ]]; then echo line fi done < "$filename" $key is a string ...
6
votes
2answers
2k views

bash completion not working for one user

On my Debian Wheezy system I have several users. For one user, lets call him martin (UID 1000) bash completion is not working. It works fine for all other users, even though they all use the same $...
0
votes
1answer
252 views

Where does bash store the time commands were executed?

Enabling history to display time via export HISTTIMEFORMAT='%F %T ' shows the times of the commands but .bash_history doesn't contain any times. Where does bash store the times the commands were ...
2
votes
1answer
643 views

How can I use “emulate sh” in zsh to work with “. myscript.sh”?

I've been using emulate sh -c ". $HOME/myscript.sh" and it's working so far. However, if I'm at ~ and try to do emulate sh -c ". myscript.sh", I get .: no such file or directory: myscript.sh.. Why?
2
votes
2answers
12k views

Bash script calls expect script with master SSH connection

I'm trying to write a bash script that calls an expect script to establish a master SSH connection to be used for the remaining SSH commands in the bash script. ~/.ssh/config: ControlMaster auto ...
4
votes
1answer
294 views

CPU is free, yet bash script not utilizing all CPU resources

I ran a simple script to generate a large (10000000 lines) csv file with 6 fields in which some fields changed in each line/row, using a while loop. The machine had all (32) CPUs free, lot of RAM (~31 ...
6
votes
3answers
2k views

emulate tail with sed

I have a mini-system with only limited number of binaries (bash,cp,cat,sed, ...). I don't have tail command, and I am wondering if I could emulate tail functionality with sed cat foo.txt | tail -n 10 ...
2
votes
2answers
249 views

Error message on terminal despite using 2> symbol

Why does this command show error message despite using 2> symbol? cat < foo 2>bar bash : cannot open foo : No such file or directory
1
vote
1answer
128 views

Problem with command promp cycling when using colors and trying to put git branches on the command prompt

tl;dr: I want my command prompt to be customizable with any color I want and also display the current git branch that I am on. I am aware that there are at least six different post asking an ...
-1
votes
1answer
711 views

How to use variables in sed

I want to print out the lines of a file between two indices in a Bash script. I have the file name and indices as variables I tried doing this sed -n "$2,$3p" $1 sed: -e expression #1, char 4: ...
0
votes
2answers
1k views

Switch between runlevel with init command in bash script … init 3 to init 5

I need your help with bash script that I’m trying to build. To keep things simple I will make it short: The script starts running once it’s gets to run level 5 so i copied the script to /etc/rc.d/rc5....
1
vote
1answer
147 views

What's the practical difference between `command` and $(command)? [duplicate]

Both give the output of the command, so what is the semantic difference between the two? Some reading led me to suspect is that $(command) is Bash syntax, and the back quotes are integrated into Unix ...
0
votes
2answers
470 views

Moving dot files using bash and creating symlinks

Trying to move selected dotfiles from ~ directory into new directory dotfiles and create symbink, with this code: 1 #!/bin/bash. 2 # This file moves selected files to newly created .dotfile ...
2
votes
4answers
1k views

How to edit/delete a .dot_file on mac without using Terminal

When I start Terminal I can not control it. It starts executing an endless loop repeating that some alias does not exist. Because of this I am not able to edit this file using a program such as vim. ...
4
votes
1answer
849 views

How to cd into a directory with the name “-”? [duplicate]

I tried to cd into a directory named - that I created for experimenting. I could not from Bash. How do I cd into it? With Nautilus on Ubuntu 13.10 I could easily do this, and even create files inside ...
11
votes
1answer
678 views

Clear old prompt lines in bash to save scroll space

My terminal theme used to be like this, But I thought the prompt wasted so much space. And later I got an idea that I could clean the prompt every time I ran a command. I was using bash, one of ...
1
vote
2answers
1k views

Tail multiple files and output as additional column with 'find' results

Would like to pull the last line of text from a specific (multiple) files in a directory. Additionally, I'd like the results to be in a more traditional column format (like ls) with path, rather than ...
1
vote
1answer
68 views

How to create an alias for opening a directory on Mac

Trying to create an alias hello. After typing hello in Terminal, then vi opens hello_folder. Now, this code returns: $ hello -bash: hello: command not found 1 #!/bin/bash 2 cd ~/Documents/ ...
5
votes
2answers
2k views

Pass multiple commands to flock

flock -x -w 5 ~/counter.txt 'COUNTER=$(cat ~/counter.txt); echo $((COUNTER + 1)) > ~/counter.txt' How would I pass multiple comands to flock as in the example above? As far as I understand, ...
9
votes
2answers
4k views

How to store an image file in bash variable?

After I use the following command, pngString="$(cat example.png)" echo -n "$pngString" > tmp.png I can't open the tmp.png as a PNG file. Maybe some information is lost when I use $pngString ...
1
vote
2answers
638 views

How to loop through xargs where each script uses a common env variable

Is it possible to initiate 10 of the same shell scripts which also initiate more copies, and have them all use the same env variable? For example: script.sh: #!/bin/bash export COUNTER=$((COUNTER+1)...
2
votes
1answer
592 views

ENV variables in relation to xargs loops

Are env variables (set using export) treated differently when the same script is run multiple times simultaneously? That's a weird question, so here's an example I built out which is similar to my ...
0
votes
2answers
969 views

if env variable exists then exit out of script

#!/bin/bash if [[ -n "$MYVAR" ]]; then exit; fi # otherwise the rest of the script continues... I'm trying to exit out of a shell script if a certain ENV variable is 0. The script above does not ...
1
vote
1answer
572 views

Using sed output in another script or command

How can I use the output of sed in another script? For example (this doesn't work): sed -n "$COUNTER",1p /domains.csv | wget or sed -n "$COUNTER",1p /domains.csv > /myScript.sh As far as I ...
2
votes
3answers
3k views

Is it possible to split file and append the pieces with same extension in one liner?

I did it in two commands --- one for splitting, and one for moving. I can't seem to find my way around it such as to have it all done with one line. What I did was: split.exe --bytes=2300k -d ...
7
votes
2answers
911 views

How do you get descriptions of the available `shopt` options?

What is the canonical way for accessing the local documentation on any available Shell Options builtin with shopt? I'm using Ubuntu 12.04 and can run help shopt to get a description of what shopt ...
9
votes
5answers
9k 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 ...
2
votes
1answer
179 views

Simulating READLINE_LINE in Bash < 4.0

I am trying to make some of my code bash 3.X compatible and I have a key-binding that utilizes READLINE_LINE inside its callback function. 3.0 versions of Bash don't supply the READLINE_LINE, so I ...
5
votes
4answers
5k views

Detect if mouse button is pressed, then invoke a script or command

Is there any way to get mouse button state from bash? Xdotool can only get mouse location. I'd like to set something up where I can define a rule where when a mouse button is pressed, a script can ...
1
vote
3answers
254 views

apply specific command for each git repository

I want compress all the git repositories on my computer (say in ~). I.e., for each directory {}, that contains directory or file (in case of submodules) named .git, I want to execute git gc --...
0
votes
1answer
49 views

rearranging from colum to row in a csv [duplicate]

I have a CSV file that presently has an output like this 1 2 3 4 5 what I need to do is reconfigure the output as follows 1 2 3 4 5 all the entry data on one line, any help would be greatly ...
11
votes
3answers
17k views

How to add a function to .bash_profile/.profile/bashrc in shell?

I have a function which converts epoch time to date. Here is the definition date1(){ date -d @$1 } I'd like to be able to write: $ date1 xxxyyy Where xxxyyy is the parameter I pass into my ...
2
votes
4answers
5k views

How to check the process along with its arguments in process list?

I have written a script where i need to pass several arguments with the same script, the script is being executed after a certain time using cron. In order to make sure that there are no multiple ...
1
vote
2answers
929 views

Use xargs input in eval command [duplicate]

I have a file "commands.php" that dynamically generates bash commands. For example, one line is: # - commands.php ssh me@123.123.123.123 echo "text" > file; reboot; How can I use the output of ...
3
votes
2answers
4k views

xargs loop with input variable for use in multi-command

I have a text file with various IP addresses. I would like to cycle through each, and issue a command: cat ips.txt | xargs -L 1 `ssh me@__IP__ echo "text" > file; reboot;` But I'm unsure how ...
3
votes
1answer
614 views

How does the piping in this command ultimately achieve to kill the process?

I have seen the following line in a bash script for killing a process(in this case started with the command loadgen): ps xww | grep -i "loadgen" | grep "PATTERNMATCH_FACT.xml" | cut -c1-5 | xargs -i ...
-4
votes
2answers
131 views

z in bash script returns zero [closed]

#[ -z "" ] #echo $? returns 0 #[ -a "" ] #echo $? returns 1 except z all other alphabets throw 1 What might be the reason?
0
votes
1answer
672 views

How to write conditional if statement in bash shell script?

I have a below shell script which will get the latest folder from my current directory in machineB and machineC. So I came up with the below command which will find me the latest folder inside - /bat/...
2
votes
2answers
333 views

How to cd into a directory as part of shell script and do a word count of files?

I am trying to get the latest folder inside my directory in machineB and machineC. So I came up with the below command which will find me the latest folder inside - `/bat/data/snapshot` And that ...
1
vote
2answers
74 views

Running a program to output in Dutch

I'm running KDE Arch linux and trying to update my system using pacman and have it output in Dutch. I've tried the following sudo LANG=nl_NL.UTF-8 pacman -Syy sudo KDE_LANG=nl_NL.UTF-8 pacman -Syy ...
1
vote
3answers
229 views

How do I iterate the list and copy the files from machineB and machineC efficiently?

I need to scp the files from machineB and machineC to machineA. I am running my below shell script from machineA. I have setup the ssh keys properly. If the files are not there in machineB, then it ...
9
votes
4answers
2k views

Pass a Function to another user in Bash?

Is there any way that I can pass a Function from one user to another user? For example, I have a small Bash script that I execute as Root: #!/bin/bash user_func(){ whoami exit } su vagrant -c '...
2
votes
2answers
73 views

Processes lose attachment to shell when started via bash -x

Normally, if I run emacs & and then close the shell, emacs will exit. However, if I run bash -x foo.foo (where foo.foo is a script that runs emacs &), then emacs will remain open even when I ...
0
votes
2answers
881 views

Convert perl script to bash

The following script it's about monitoring some logs, the $timestamp is at log at every line that something happens. Example: 03:19:13.4 Begin summary update for ads.doc.inventory....
3
votes
1answer
440 views

Using a variable inside a sequence of commands in bash to supplement an existing string - syntax error or flawed design?

I'm using the following sequence of commands in my .bashrc file to alter the appearance of my linux terminal. It fills the screen line by line with a pattern made out of characters. There is no ...
2
votes
2answers
773 views

What is the best way to check if file has changed in Bash and keep 15 last copies of it?

What would be the best way to write a bash script and run it from cron (every hour) that: Would see if a file in a directory has changed If changed, make a copy with incrementing version number and ...
4
votes
4answers
505 views

Continue for loop by keyboard

I have user account on a linux machine which I do not know its exact IP address. But I know a range which it is ran on one of them. I want to check which server is my desired server. There are some ...
2
votes
1answer
391 views

How to avoid warnings from subshells if the function in PROMPT_COMMAND is not defined?

I'm using the following code to get a nice prompt (including git information etc.): function set_prompt { # magic happens in here ;) } export PROMPT_COMMAND='set_prompt' However, sometimes I ...
4
votes
1answer
121 views

Where is the description of man sections' contents?

I have read in many places that section 1 is about User Commands , section 2 about kernel API , section 3 about C library ...so on and so forth. My question is this: How do you get to the short ...