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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0answers
27 views

SSH Session Hangs - Custom Way of Checking It

So, the hanging of the session is not the issue by itself - I am aware of it, I know its root cause. I am interested in a rather custom solution for checking if the session hangs. I am inspired by ...
5
votes
3answers
8k views

Bash script wait for processes and get return code

I am trying to create a script which will start many background command. For each background command I need to get the return code. I have been trying the following script : #!/bin/bash set -x ...
1
vote
1answer
16 views

Awk - matching on 2 columns for differents lines

Given this file: 92157768877;Sof_deme_Fort_Email_am_%yyyy%%mm%%dd%;EMAIL;20/02/2015;1;0;0 92157768877;Sof_trav_Fort_Email_am_%yyyy%%mm%%dd%;EMAIL;20/02/2015;1;0;0 ...
2
votes
1answer
56 views

Expanding paths in Bash variables into sed expressions

I would like to ask what's wrong with this line? sed -i "/$PWD/a\ Hello World" historia.txt when I had it in this '' except for "" it was working, of course without expanded variable.
3
votes
3answers
242 views

Switch user in a shell script without entering the password

I'm running a shell script using terminal from userA. In the middle of this shell script, I switch to userB user using su, but this asks me for the password of userB and I have to manually enter the ...
0
votes
0answers
19 views

How to read - in Linux? [duplicate]

Whenever I am dictating linux CLI commands to someone I get in a dilemma on how to say - in English. For example, to dictate ls -la I sometimes say L S minus L A or L S hyphen L A or L S dash L A. Is ...
5
votes
4answers
4k views

Bash, how to let some background processes run but wait for others?

I have (yet) another wait, &, && control flow question.. Say I have a script something like this where I want to do as much work at the same time as possible: # may take some hours ...
1
vote
2answers
33 views

Need special validation for shell script

I want to create a bash script which will have lot of options while executing. # script.sh --dry-run --user <parameter1> --pass <parameter2> I heard about getopt option but looks like ...
3
votes
5answers
82 views

Get PID of process started by time

Say I run time ./a.out, then I can get the PID of time by the variable $!. But how do I get the PID of a.out? Of course, I could parse the output of ps, but I want a more elegant solution. I've ...
1
vote
4answers
62 views

Delete all files in a directory

I have a directory which includes some files and some folders containing other files. I'm trying to remove these files in the main directory without touching the folders or their contents. I'm using ...
1
vote
2answers
44 views

Swap line containing pattern with next line

I currently have the following code which nicely outputs some information about the wireless networks around me: sudo iw wlan0 scan | sed -nr '/SSID: |signal: |primary channel: /p' | sed ...
2
votes
3answers
90 views

Comparing strings

I am having trouble comparing two strings. Even though they are identical when printed, my if statement returns false. #!/bin/bash string1="HDMI" string2="PC Speaker" hash=$(pacmd list-sinks | ...
2
votes
1answer
57 views

How to merge these commands into one?

This is what I am wanting to do: Convert a folder of HTML files into markdown, also copying over the the xml metadata of each of the HTML files by converting into YAML. I have done research and come ...
1
vote
1answer
39 views

BASH: looping through ls [duplicate]

I'm having trouble with this piece of code: 22 for filename in "$( ls "$1" | grep ".*\.flac$" )"; do 23 file_path="$1${filename}" 24 ffmpeg -i "${file_path}" -f ...
2
votes
0answers
30 views

How to sort files by their dates into timestamped folders? [duplicate]

I want to sort about 2500 images every day into folders with a timestamp. So far I have this script but it's not working.... for x in *.jpg; do d=$(date -r "$x" +%Y-%m-%d) mkdir -p "$d" mv -- "$x" ...
0
votes
1answer
28 views

Print nth pipeline command in bash

In bash, the PIPESTATUS array holds the return values of commands in a pipeline. Suppose that in the pipeline cmd1 | cmd2 | cmd3, the second command returns an error. Checking PIPESTATUS gives the ...
0
votes
1answer
51 views

Translate Windows batch script into a bash script for Linux

I'm new to Linux and am trying to find the equivalent of this from Windows @echo off if ".%1" == "." goto TellSyntax set ...
1
vote
2answers
47 views

sh -c: Unterminated quoted string error [duplicate]

I've spent hours trying to understand the following error. My Script CMD="sh -c 'echo \"a\"'" $CMD Error: "a"': 1: "a"': Syntax error: Unterminated quoted string of course when I do echo $CMD ...
-1
votes
1answer
70 views

How to write a auto-completion bash script?

I want to run some functions (which I created in ./.bash_func) in terminal with some files located somewhere. When I type the function and hit Tab Tab I want to list the files located in ./scipts like ...
2
votes
1answer
40 views

How to protect against purge of bash history?

Following the answer: When closing multiple bash instances at the same time, there is a known race condition that may cause the history to be cleared. This occurs because there is no locking ...
0
votes
3answers
613 views

Solaris jdk 7 installation error java -version No such file or directory

Am trying to follow this website for instruction on how to install jdk for Solaris 10 with the following information: $ isainfo -v 64-bit amd64 applications ssse3 tscp sse3 sse2 sse fxsr mmx ...
0
votes
4answers
69 views

Is there a quick way to install packages if there is a prompt?

If I want to install a package, wlhunag: ~ $ pip install django The program 'pip' is currently not installed. You can install it by typing: sudo apt-get install python-pip wlhunag: ~ $ I wonder if ...
1
vote
2answers
274 views

How to put $@ in quotes?

My bash script looks like this: #!/bin/bash grep -r --color=always $@ . | nolong The file is saved in /usr/bin/findstr Everything's ok when I run this: findstr hello But when I run this: ...
1
vote
2answers
69 views

Why is grep searching more than the files I want with asterisk?

Deep within a bash script I have grep -Ech 'string1|string2' /server/directory/$servername_log_20150312* | awk ... I was getting the "too many arguments" error so I turned on set -x and I see that ...
5
votes
3answers
406 views

Which of the following codes will run in the same process of the current shell

A. { echo "Hello World"; } >outputfile B. ( echo "Hello World" ) >outputfile C. ./anothershell.sh D. /bin/echo "Hello World" Which is right? And what kind of command can run in the same ...
1
vote
2answers
390 views

Alternative for jq in debian wheezy to parse json in bash

In Ubuntu you can simply install jq apt-get install jq but on debian it is not in the repository. Is there an alternative commandline to parse a JSON string on the console? maybe you can achieve ...
2
votes
2answers
40 views

Is shell parent of all the processes in linux

I have been trying to understand shell scopes and environment in depth. I have been reading about how if we do export VARIABLE=VALUE it will be available in subshell. So I wanted to ask a question I ...
8
votes
1answer
115 views

Why does brace expansion range use two dots instead of three (ellipsis)?

I finally understood/discovered why I never got to using bash's (and also zsh's) brace expansion range properly: the syntax is {1..10} instead of what I assumed to be an ellipsis, i.e. {1...10}. May ...
1
vote
1answer
79 views

Bash: Looping through a string

I have a variable Vmac that stores values of multiple MAC addresses, collected from wmic call as follows: Vmac=`wmic --delimiter="," --authentication-file=/path/to/file //IP-ADDR "Select ...
2
votes
1answer
256 views

bash: Source: command not found

I keep getting the following error when I open my terminal. I am running Fedora 19. bash: Source: command not found The above error also caused my screen to go blank when I tried to login. I then ...
0
votes
3answers
92 views

How to [constantly] read the last line of a file?

I have client filtering out data from an live MQTT stream which writes the data into a myfile.csv file, here are the last four lines: 1426134425,m,NWRL,MSV,001,d,SVlts,139,1840343,26089,28529,15987 ...
5
votes
4answers
374 views

list graphical processes from terminal

Do no confuse the question here with how to list processes graphically, that is not what I am asking. In the Terminal, how can i see which processes have a GUI? as in things like firefox, vlc, ...
11
votes
2answers
3k views

What is the difference between “du -sh *” and “du -sh ./*”?

The title says it all. What's the difference between those 2 commands? NOTE: I'm more interested in the * and ./* part.
3
votes
3answers
118 views

Understanding Bash's Command Substitution

I am trying to understand how exactly Bash treats the following line: $(< $FILE) According to the Bash man page, this is equivalent to: $(cat $FILE) and I can follow the line of reasoning for ...
1
vote
1answer
62 views

Environment Variables not getting set in bash_profile

I have my bash_profile environment setting as follows: if [ `hostname` = "devoraebs01" ]; then echo `hostname -f` . /appl_top/deverp/appl/APPSDEVERP_devoraebs01.env When I log into this host, ...
1
vote
2answers
40 views

Rename files depending on their parent directory

I have a main directory, let's say main. This main directory has some folders, among which are three folders named ccc ddd and lll, which are the only folders I want to target and work on. Each of ...
29
votes
3answers
7k 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 ...
44
votes
1answer
1k views

Security implications of forgetting to quote a variable in bash/POSIX shells

If you've been following unix.stackexchange.com for a while, you should hopefully know by now that leaving a variable unquoted in list context (as in echo $var) in Bourne/POSIX shells (zsh being the ...
2
votes
1answer
29 views

Copy files that partially matches another files in another location

I have a list of jpeg files in a directory like this (below is just a sample, like the structure is the same but this there are many fo0# sub-folders, not only fo01 and fo01, where each of these ...
4
votes
2answers
79 views

Replace string in a file with another where both are saved in variables

I want to replace a string found in a file with another string, but both have a special character (in this example it is a . char) e.g 1.0 and 2.0. So this is the command currently used: sed -i ...
1
vote
1answer
24 views

NginX + PHP-FPM displays blank php pages

I have a problem where my server running NginX with php-fpm loads blank PHP pages (strangely except for my phpinfo.php file, which loads normally). If I put an index.html page in the same directory ...
24
votes
3answers
18k views

How to remove a single line from history?

I'm working in Mac OSX, so I guess I'm using bash...? Sometimes I enter something that I don't want to be remembered in the history. How do I remove it?
2
votes
1answer
2k views

Can I change uuid for network interface in ifcfg-eth* using uuidgen?

I'm creating a script which configuration the network interfaces. The script which generates /etc/udev/rules.d/70-persistent-net.rules and names interfaces to my preference. In CentOS 6.5, my ...
5
votes
2answers
1k views

Strange behaviour of uninitialized arrays and unset arrays

I'm writing a script and I discovered some unexpected behaviour of uninitialized and unset array variables that I do not understand. First of all, the length: $ echo ${#notset[@]} 0 $ uninitialized= ...
0
votes
1answer
14 views

displaying rate information from stream of numbers

Are there any command line tools that would make it easy to display rate information based on a stream of newline separated numbers? For example average "count" per second/minute and total "count" so ...
2
votes
2answers
196 views

monitor linux file systems using df

I use df -kh to get the file system usage, but the trouble is if there is any NFS mount failure in any of the boxes the command will hang. Is there a better way to monitor file systems other than df ...
0
votes
2answers
59 views

ssh inside a script with 'command' instead of “command”

I am trying to run commands on various nodes of our cluster automatically via a simples script. I have seen that I can run: #!/bin/bash echo "Machine: "$HOSTNAME; ssh machine2 'echo Machine: ...
0
votes
2answers
39 views

Script with multiple arithmetic conditions failing

I'm experiencing problems with a script converting numbers to bytes. If the number is large enough to hit gigabytes or terabytes, the script runs as it should. If the number converts to kilobytes, ...
1
vote
4answers
43 views

echo \\* - bash backslash escape behavior, is it evaluated backwards?

So in bash, When I do echo \* * This seems right, as * is escaped and taken literally. But I can't understand that, when I do echo \\* \* I thought the first backslash escaped the second one ...
-1
votes
1answer
41 views

permission denied on running script despite +x

Script is on exec partition (under /home/~~~ ) and have +x flag (-rwxr-xr-x ). executable on bash shell (not with script) but not on script. script is quite simple. #!/bin/bash data=cat ...