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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1
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4answers
80 views

Traverse all subdirectories in and do something in Unix shell script

I am new to bash scripting. I am working on a shell script and got stuck from last 3 days. I want my shell script to visit all subdirectories in a main directory. Do something in directories, sent ...
4
votes
5answers
154 views

How can I use a wildcard to match just files, not directories?

I have a folder called home/homeLife I have a file called home1 home2 and home3 stored in /home I want to move all files that start with home* to home/homeLife/.. I typed mv home* /home/homeLife ...
2
votes
1answer
69 views

How to add number to awk array elements?

If I have the following bash variable: $ echo "${pos}" 201 719 744 205 354 ...the following produces... !#bin/bash ( IFS=: awk -v str2="$pos" -v sep="[$IFS]" ' BEGIN { ...
21
votes
11answers
8k views

Object-oriented shell for *nix

Preface: I love bash and have no intention of starting any sort of argument or holy-war, and hopefully this is not an extremely naive question. This question is somewhat related to this post on ...
1
vote
3answers
35 views

Variable related to variable

I want to get effect like bellow but I do not know how: $> A='/dir' $> B="$A/bin" $> echo $B /dir/bin $> A='/other' $> echo $B /other/bin any ideas?
1
vote
2answers
43 views

Single or Double quotes when defining an alias?

I know that contents of double quotes are expanded, whereas the contents of single quotes are not, such that echo '$1' gives $1 where as echo "$1" gives <the argument - blank in this ...
3
votes
5answers
282 views

How do I loop over output from shuf?

If I do gshuf -e $(seq 1 10) in bash it will print the numbers 1 thru 10 in random order. But if I do: a=$(shuf -e $(seq 1 10)) for i in "${a[@]}" do echo $i echo "next" done It prints ...
5
votes
2answers
66 views

Is it possible for bash completion to cycle through the alternatives?

When using bash completion and an a number of characters have been entered, tabbing ceases to work then the prefix you have typed is matched by more than one of the possibilities. Is there a way to ...
0
votes
2answers
37 views

While Read loop to email

I'm having issues with a script i'm writing. I'm trying to monitor free disk space, and to have an email generated for each filesystem over a certain threshold. When using this script with 'echo' ...
2
votes
1answer
44 views

Push onto array with find exec

I want to iterate over all the files found by find and add each one to an array. Here's what I have so far: myarray=() find . -name '*.php' -exec myarray\+=\({}\) \; echo "${myarray[@]}" Instead, ...
2
votes
1answer
39 views

sanely run all scripts in a directory

i would like to create a shell-script that in turn runs all scripts it finds in a given directory. following restrictions should apply: the scripts ought to be run in alphabetical order ...
1
vote
2answers
48 views

Bash: How to create an alias in .bashrc for awk with parameters

I'm trying to add an alias in .bashrc file as follows: ... alias cutf="_cutf" ... _cutf() { awk 'NR >= $2 && NR <= $3 { print }' < $1 } (The function's goal is to show the ...
0
votes
3answers
44 views

How can I capture the common characters between two strings

I'm looking to compare two strings and capture the common part e.g. FILE0000010985.LOG FILE0000010999.LOG FILE0000011000.LOG If I compare 1 to 2, I want the output to be ...
7
votes
2answers
21k views

Can I redirect output to a log file and background a process at the same time?

Can I redirect output to a log file and background a process at the same time? In other words, can I do something like this? nohup java -jar myProgram.jar 2>$1 > output.log & Or, is that ...
0
votes
1answer
38 views

Parse header in a file and based on the header replace a value in the file

I have a problem I need help with. I'm not very experienced with awk, but it seems to be a good tool for this job. I have the following file Field1|Field2|Field3|Field4|Field5 a|b|c|d|e 1|2|3|4|5 ...
3
votes
1answer
46 views

How to sort an associative array and retain the keys?

I have an array with filenames as keys and a numerical value as values. MYARRAY[00001.jpg] = 31 MYARRAY[00002.jpg] = 200 MYARRAY[00003.jpg] = 98 I need to sort them so they are ordered by value. ...
0
votes
1answer
2k views

Changing title without changing prompt on Cygwin

I have the following shell script function from this site that allows me to change the title in both Putty and Cygwin. In Putty connected to a Linux host it changes the title and leaves the prompt as ...
8
votes
2answers
6k views

What do the bash-builtins 'set' and 'export' do?

I am at a bit of a loss as to the purpose of set and export in Bash (and I guess probably other shells too). I would think it is for setting environment variables, but that can be done just with ...
4
votes
2answers
118 views

Running a script during booting/startup; init.d vs cron @reboot

I am currently trying to understand the difference between init.d and cron @reboot for running a script at startup/booting of the system. The use of @reboot (this method was mentioned in this forum ...
8
votes
3answers
34k views

linux + add X days to date and get new virtual date

I have Linux ( RH 5.3) machine I need to add/calculate 10 days plus date so then I will get new date (expiration date)) for example # date Sun Sep 11 07:59:16 IST 2012 So I need to get ...
0
votes
2answers
48 views

linux curl POST request not working

I am trying to make a POST request using curl to retrieve exam results from the page : result odd .... I am using the following syntax but various errors are showing up (like content has moved ...
1
vote
1answer
26 views

What is the proper bash method of prompting the user for administrative password before backing up the usb data to the computer?

mate-terminal --window-with-profile=PROFILENAME="Hold the terminal open" -e "sudo rsync -azvu --log-file=/var/log/simplebackup.log --append-verify --exclude '.gvfs' /media/user/usb/ ...
0
votes
1answer
53 views

How to run privileged bash script as non-root? [duplicate]

I created a simple bash script which contains the command ifconfig. In general I want to execute such a privileged script to run as non-root user. I have tried hown root:users ./path/to/script.sh ...
3
votes
2answers
107 views

Repeatedly execute bash command while there's no output from another process

I'm running fs_usage to detect access to an object on my filesystem. sudo fs_usage -w | grep -E 'object' I now want to run a touch command on that object every 5 seconds as long as there's no new ...
3
votes
2answers
36 views

command substition for multiline output of command?

How can I make the following command substitution work? $ time real 0m0.000s user 0m0.000s sys 0m0.000s $ oldtime="$(time)" bash: command substitution: line 23: syntax error near unexpected ...
1
vote
1answer
79 views

redirecting output of running background job in bash

in bash I have some jobs running, in background. They are always producing random irrelevant error messages that pollute the terminal. I am not always so prompt to start them with the 2>&1 > ...
2
votes
1answer
44 views

monitor multiple pids with top

I want to monitor memory usage for several processes and came up with a command like this: ps aux |grep -e postgres -e unicorn -e nginx|cut -d' ' -f2|for i in $(xargs); do echo $i; done 16112 16113 ...
1
vote
1answer
41 views

Removing passwords from terminal logs in CentOS 7

Sometimes a user gives a typo when they are trying to give a password after typing a sensitive command, such as su - . The user then will assume they are being given another password request, and ...
1
vote
1answer
45 views

Dynamic ~/.ssh/config

I'd like make my ~/.ssh/config file dynamically generated by a shell script (or anything else that prints to STDOUT). Is there a UNIX trick to make reading a file result in executing a command & ...
0
votes
0answers
52 views

'cp:cannot access file' error in script?

This is the code: #!/bin/bash $REPORT_PATH='/data/operational/logs' cp "$(`ls -t | head -1`)" "$REPORT_PATH/new_file" This gives error 'cp:cannot access pda_param'. pda_param file is o/p of ls ...
3
votes
4answers
2k 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 ...
2
votes
0answers
48 views

How do I sleep or wait a process when memory is running low?

I have created a script allows a user to start/stop/assign memory to/check memory/assign a value (such as %)/check that value and reset priority on 6 processes which I have created. However, this ...
8
votes
2answers
2k views

How to export variables that are set, all at once?

set command displays all the local variables like below. How do I export these variables all at once? >set a=123 b="asd asd" c="hello world"
1
vote
1answer
49 views

Bash cannot see PATH update

I am running Debian on a VM. I login to the GUI and go to Applications > Accessories > Terminal. # echo shell: /bin/bash I modified ENV_SUPATH, ENV_PATH inside of /etc/login.defs. I restarted ...
1
vote
1answer
44 views

How do you derive a decimal from a math operation involving a variable?

I'm trying to find derive SCALEFACTOR which is basically 10000/(sum of 4th column in a file). How do I get a decimal from the output? Appreciate any help in advance. #!/bin/bash ...
0
votes
2answers
48 views

Will “tail -100 | sed -n 1p” only read one line?

I'm searching backwards from the end of a file, it's probably easiest to explain by showing my code: enough=0 numberOfLines=100 fileName="/path/to.file" # Tail the last $numberOfLines lines; if the ...
-1
votes
1answer
57 views

Linux why do i have to run commands instead of running the bash file [duplicate]

In order to run an executable file, I need to run all the commands in the below bash file first, so I just put those commands in the bash file and run the bash file first, but running the bash file ...
3
votes
1answer
84 views

Bash scripting to scan files for words and create report

Ok yes this is a homework assignment BUT I am NOT looking to have the answers given to me. The scenario is that I need a script that searches all my users home directories for bad words. I need the ...
7
votes
3answers
7k 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 ...
1
vote
2answers
999 views

How to round a float value to int in bash

I will get value like 2743410360.320 and I want value like 2743410360 to a variable. I tried INTValueOfGB=$ echo "($gb+0.5)/1" | bc But I am getting (standard_in) 1: syntax error
0
votes
2answers
53 views

Multiple variable expansion modifiers in the same expression

Why does the following idiom not work in bash 4.1.0? if [[ "${FUNCNAME[*]:1/$FUNCNAME/}" != "${FUNCNAME[*]:1}" ]] Here it is in context... function isCircularRef_test () { # ### Seems like ...
0
votes
2answers
189 views

Detecting circular references in bash 4.1.0

The following function is called as the first line in every other function in order to handle optional debugging, context sensitive help, etc. Because of this, calling a function that in turn calls ...
4
votes
1answer
1k views

Forward SIGTERM to child in Bash

I have a Bash script, which looks similar to this: #!/bin/bash echo "Doing some initial work...."; /bin/start/main/server --nodaemon Now if the bash shell running the script receives a SIGTERM ...
0
votes
0answers
8 views

Specify “any sequence of digits” to ‘compgen’

How can I get compgen to return matches for “any valid sequence of digits”? The Bash compgen command is used to generate completion matches in Bash programmable completion. There are many options for ...
2
votes
3answers
75 views

Copy files to a destination folder only if the files already exist. but the source files have a different file extension

Copy files to a destination folder only if the files already exist. but the source files have a different file extension. i.e I have a backup of some files with ".desktop.in" extension and I want to ...
5
votes
2answers
8k views

Global bash_profile

I realize there are /etc/profile and /etc/bashrc files for setting global environment variables and maybe I'm just misunderstanding their purposes, but... Is there a global bash_profile file? I'm ...
12
votes
1answer
722 views

Why is architecture listed thrice in uname -a?

$ uname -a Linux 3.13.0-29-generic #53-Ubuntu SMP Wed Jun 4 21:00:20 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux Running ubuntu 12.04.1 LTS. Why does it have the architecture (x86_64) listed thrice?
6
votes
3answers
1k views

Passing arguments from a file to a bash script

I' ve got this situation: ./ ./myscript.sh ./arguments.txt ./test.sh Inside myscript.sh, i have to run the file test.sh, passing to it the arguments contained inside arguments.txt. myscript.sh is: ...
0
votes
0answers
19 views

rc.local, su, and a bash script

I've got a bash script /usr/local/bin/startvnc that's just this: #!/bin/bash vncserver -kill :$1 sleep 2 vncserver -geometry 1250x950 :$1 And it gets called, per user, from /etc/rc.local like this: ...
14
votes
3answers
479 views

How do I explicitly and safely force the use of a built-in command in bash

There's a similar question that deals with the 'wrapping' scenario, where you want to replace for example cd with a command that calls the builtin cd. However, in light of shellshock et al and ...