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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2
votes
0answers
22 views

Differences between declared, defined, and set

In shell, what are the differences between a variable that is declared, defined and set? Does "declared" mean the identifier of the variable exists, but the storage and value of the variable do ...
85
votes
3answers
51k views

Why does my shell script choke on whitespace or other special characters?

Or, an introductory guide to robust filename handling and other string passing in shell scripts. I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some ...
2
votes
3answers
32 views

set variable inside heredoc and use them outside

I'm trying to set the variable 'count' while running the command inside a heredoc together with timeout, but I'm unable to get the 'count' variable outside the heredoc. How can I achieve that? My ...
0
votes
2answers
32 views

Carriage returns are prevent sed reading all my files

I have a long list of folders, inside every folder I have the file "log.dat". I wanted to read the value of a specific line inside this file. I saved the folders names in a file "All.txt", in the ...
-1
votes
1answer
39 views

Understand the meaning of `$_`

Could you explain the following sentences from Bash manual about $_, especially the parts in bold, maybe with some examples? At shell startup, set to the absolute pathname used to invoke the ...
-1
votes
1answer
22 views

How to set gdb run in /bin/sh [on hold]

Clion (c++ IDE) uses gdb as a debugger but it won't work (ERROR 127) unless we set /bin/sh as a SHELL. Is it possible to put a script or smth before IDEA opens the debugger?
17
votes
8answers
14k 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 ...
0
votes
1answer
23 views

What is the meaning of $0 in the Bash shell

From Bash Manual $0 Expands to the name of the shell or shell script. This is set at shell initialization. If Bash is invoked with a file of commands (see Section 3.8 [Shell Scripts], ...
1
vote
1answer
20 views

Are the null string and “” the same string?

Bash manual says: A parameter is set if it has been assigned a value. The null string is a valid value. ... If value is not given, the variable is assigned the null string. Is the ...
1
vote
1answer
29 views

No permissions?

Output of ls -l: drwxrwxrwx 16 btsync btsync 4096 Feb 25 15:41 documents I can cd into the folder no problems. Now: sudo chmod 776 documents I can no longer cd into the folder: bash: cd: ...
44
votes
2answers
37k views

How to suspend and resume processes

In the bash terminal I can hit Control+Z to suspend any running process... then I can type fg to resume the process. Is it possible to suspend a process if I only have it's PID? And if so, what ...
1
vote
1answer
57 views

Pattern matching [duplicate]

I am trying to follow Bash Cookbook to learn about Bash Scripting. I am on example 6.8 Testing with Regular Expression. I have the following script: #!/usr/bin/env bash # cookbook filename: ...
10
votes
2answers
344 views

What is “<Esc>Kv” in bash

When I am in bash and press Esc, Shift+K, V, bash fires up $EDITOR with a filename similar to /tmp/bash-fc-186566385. Why is that and what is its purpose? I probably need to mention that I am ...
1
vote
1answer
18 views

mv command with path wildcard containing random string

Im trying to move a file to a path which has a random string that I cannot know in advance ~/.config/foldername/45fhiu84.dev-edition/subfolder/ I have tried mv ~/Downloads/myfile.txt ...
1
vote
1answer
838 views

bash $(printf “%s\n”) does not create multiline

I created shell script, that logs into FTP server and renames some directories. I put FTP commands in multiline string like so # !/bin/sh ftp -inv $HOST << EOF user $USER $PASSWORD $COMMANDS ...
1
vote
2answers
57 views

Bash commands not found

I use CentOS 7 and I install anaconda and some tools, after that some basic command like clear which not work. [zhilevan@localhost ~]$ clear bash: clear: command not found... when I echo $PATH I ...
7
votes
4answers
784 views

What is the setting in bash for globbing, to control whether * matches dot files

I was surprised recently when I did something like mv ./* ../somedirectory and found that files like .gitignore were not moved. I do most of my work in zsh on OS X, and this surprise bit me in bash ...
7
votes
2answers
1k views

Are there problems with hyphens in functions, aliases, and executables?

In my testing (in Bash and Z Shell), I saw no problems with defining functions or aliases or executable shell scripts which have hyphens in the name, but I'm not confident that this will be okay in ...
3
votes
1answer
29 views

Manage Gnome GUI via Bash?

I want to power on the computer and have a Bash script to open all my programs in different Gnome work spaces. For example: Open text editor and CLI in the first work space. Open web browser A in ...
0
votes
2answers
33 views

Can we install a package through a shell script? [duplicate]

I'm trying to write a shell script so that when I reinstall my Ubuntu again. I could just run script and retain all the packages. And I'm planning to pass password in form of argument. My question ...
1
vote
3answers
273 views

Generating QR code of very big file?

I want to generate a QR code of my 4096-bit armored GPG private key. The key is so big, the program qrencode seems to fail because of its size. $ gpg --export-secret-keys --armor > ~/private.key $ ...
0
votes
1answer
64 views

Faster way to enter in command mode with vi mode in the shell

I want to use the vi mode in bash but I find the ESC key a little bit too far, as for vim. The ideal can be to keep a key pressed, like ALT or the caps lock, to stay in command mode and be in insert ...
1
vote
1answer
48 views

Needed shell script modification to show IP and host DD-WRT

I am running DD-WRT v.3.0 on my Linksys EA6500 router and I have the following script running in order to give me access to the WiFi MAC address that are currently connected to the router: echo ...
0
votes
0answers
17 views

Bash terminal shows different outputs

#!/bin/bash ionic serve &> temp.txt this code inside a script always produces the same output, ie, same output written to temp.txt file. But if I run ionic serve &> temp.txt in a ...
2
votes
1answer
35 views

Wrap and indent text using coreutils

Short version I would like to create a tabular display of multiline text, similar to the following: all Build all targets document Create documentation of source files in the subfolders ...
4
votes
1answer
823 views

KSH styling text based menu using STDERR

Is it possible to format the STDERR in order to have a better looking menu using the select command? I have a simple select select oChoice in $(<tempMenu.menu) ; do case "$oChoice" in ...
10
votes
2answers
3k views

is there a way to set coloring for cd tab complete?

I use ubuntu 11.04. Is there a way to set coloring for output after tab completion listing of a cd, ls, or etc. ? i.e. myshell@root$ cd ~/user/files/ I hit tab... myfile myfoo mybar <-- this ...
1
vote
2answers
25 views

how to set alias of command in bash that contains both single and double qoutes [duplicate]

I am not able to set alias of hexdump -e '/1 "%_ax) "' -e '/1 "%02X" "\n"' I have tried following methods but failed: alias analyze=\'hexdump -e '/1 "%_ax) "' -e '/1 "%02X" "\n"'\' (note the ...
1
vote
0answers
17 views

Use a bash array as a place-in argument list (with Midnight Commander)

I'm having a little bit of trouble figuring out how I can use a bash array for an argument list. so far, the below code does not work. The %s below is Midnight Commander specific. F=(%s); for i in ...
3
votes
3answers
39 views

Sudo-like remembrance of passwords for own scripts

I have a script which requires a password for authenticating a web service. A single password for a pre-defined user will suffice, and the password should if possible be stored securely (not plain ...
5
votes
2answers
29 views

What exactly happens if input and output file is the same?

Let's say that I execute following command: tr a-z A-Z < file > file There are two redirections: < file and > file. Both are processed before tr command and as far as I know, if there ...
2
votes
3answers
2k views

Update process name in shell, is it possible?

In C/C++ it is in general possible to do strcpy(argv[0], "new process name"). It's a hack used in malicous software to hide real process name. Is such operation possible via shell? What I want to do ...
19
votes
3answers
20k views

How can I remove an element from an array completely?

unset array[0] removes the element but still if I do echo ${array[0]} I get a null value moreover there are other ways of doing this but if an element of an array contains spaces like below ...
2
votes
4answers
30 views

How to catch and handle nonzero exit status within a Bash function?

Say I have the following (pointless) Bash function: myfunc() { ls failfailfail uptime } I run it as follows: myfunc || echo "Something is wrong." What I want to happen is ls runs (as ...
0
votes
1answer
48 views

Running .sh Script With Sudo Results In Different Output

I'm seeing some really strange behavior in a script I'm working on.What I have is an svn hook that gets run whenever a commit is made to an svn repo. It runs a sqsh command that generates another ...
1
vote
2answers
939 views

script to add users to otrs

Im looking for a fast way to import customer users into otrs (ticket system) I have an export from Active Directory with: firstname lastname password email username There is a script in the otrs/bin ...
8
votes
6answers
2k views

Serialize shell variable in bash or zsh

Is there any way to serialize a shell variable? Suppose I have a variable $VAR, and I want to be able to save it to a file or whatever, and then read it back later to get the same value back? Is ...
1
vote
1answer
23 views

copy array with array name inside string in bash

In bash 4.3 script, I have variables: environment="local" config_local=("a" "b" "b" "d") copy_from="config_${environment}" I want to copy values from array with name stored in copy_from to another ...
5
votes
3answers
11k views

Is there a way to write a script to do ftp login so I don't have to type things over and over again?

I am recently working extensively with a remote system via ftp connection, since the session time is so short that I have to re-login quite often when I finish my work on my local machine, so I need a ...
-1
votes
0answers
19 views

GREP to sort a particular error log from server log [on hold]

I want to sort particular error log from server logs. I want to see when did it last happen , and how many times a day it happened. Thank you.
0
votes
2answers
41 views

How can I forward #! through a bash script to provide indirection

Sorry if the question statement wasn't very clear. I'd like to have a bash script that I can edit to change the behavior of a bunch of other scripts. For instance--I have some groovy scripts. they ...
1
vote
3answers
63 views

Delimiter in word splitting

In Bash, word splitting is a step in command line processing. From Bash Manual The shell treats each character of $IFS as a delimiter, and splits the results of the other expansions into words ...
0
votes
2answers
136 views

No numlock in screen?

I am using a laptop and Putty on a Windows system. When I connect to my Debian Squeeze server in Bash environment, I can use the "Pos1/Home" or "End" (at the numlock part of the keyboard) to navigate ...
4
votes
2answers
39 views

Store quotes in variable to use as command line parameter Bash

I am writing a script to call a command (weka, if you are curious) a couple of times with some different parameters. One of the parameters, '-search "< stuff >" ' needs to be quoted. In some ...
1
vote
2answers
17 views

Failed to open config file '/dev/fd/63', error: No such file or directory for wpa_supplicant

When I do this: sudo wpa_supplicant -D nl80211,wext -i wlp4s0 -c <(wpa_passphrase "some ssid" "password") I get Successfully initialized wpa_supplicant Failed to open config file '/dev/fd/63', ...
0
votes
1answer
30 views

command /opt/bin/date --date '-15 minutes 2016-04-27T14:14:47' producing result many hours before stated time

I'm using the following command in an attempt to work out the time 15 minutes before the timestamp: /opt/bin/date --date "-15 minutes 2016-04-28T16:58:55" '+%Y-%m-%dT%H:%I:%S' The problem is the ...
2
votes
1answer
32 views

How do I check for the existence of a process without a failed exit code being returned?

I’m using Amazon Linux. I want to start a process provided one isn’t running already. This is a bash script I embed within a Jenkins Maven job. So I have pids=$(pidof /usr/bin/Xvfb) if [ ! -n ...
0
votes
0answers
24 views

Why does bash's readline eat tab?

My question is from Delimiter in word splitting Why does Bash not respond when I hit Tab key? What other keys does Bash eat?
1
vote
1answer
17 views

Trying to copy/paste long script with multiple EOFs, Terminal starts running half-way through

Was trying to create a text block that I could just copy and paste into a Terminal window to accomplish something (in this case, create a systemd script to do maintenance on MySQL dbs, create a timer ...
5
votes
1answer
47 views

Cannot grep jobs list when jobs called in a function

I can grep the output of jobs, and I can grep the output of a function. But why can't I grep the output of jobs when it's in a function? $ # yes, i can grep jobs $ jobs [1]+ Running vim ...