The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …).

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Hexadecimal number sequence checker in Linux?

I have a list of hexadecimal number. I would like to check whether they are in sequence or not. That is, they should be consecutive numbers, in increasing order. In other words, there should be an ...
0
votes
0answers
45 views

Shell script to send alert if mount point exceeds 75% [duplicate]

How to write shell script to send an alert if any file-system on server exceeds 75%, in one email notification instead of receiving separate alert email notification for each file-system. I am ...
2
votes
1answer
27 views

Generate SFV file, optimizing hard links

I'm currently running cfv -C -rr to generate a SFV file that contains the CRC32 checksums of all files in all subdirectories. The issue is that because there are so many hardlinks, this process is ...
1
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1answer
46 views

A question about shell and .profile,.bash_profile,.bashrc

I'm on aix 7.1,my shell is bash if i did ssh ibmunix gqlplus user/pass All works and gqlplus start,gqlplus is on /opt/freeware/bin If i did from another machine ssh ibmunix "gqlplus ...
7
votes
1answer
133 views

Why there isn't a new line at the end of quoting a subshell and passing the results to echo?

When I do ls | grep png the output of grep is: 2015-05-15-200203_1920x1080_scrot.png 2015-05-16-025536_1920x1080_scrot.png (filename,newline,filename,newline) then, echo $(ls | grep png) outputs: ...
15
votes
1answer
591 views

What's the magic that allows me to tab-complete remote files as I type an scp command?

Presumably this is a feature provided by some plugin I have enabled in my oh-my-zsh setup (I have been using zsh for many years now). I noticed ever since I added my public key to the server (now I ...
1
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2answers
60 views

How to perform grep on 'man unix_command'?

Often while going through the output of man man awk I Need to perform grep, for e.g. in man awk, I need to find the definition of a particular flag, variable etc. Can anyone tell me, what would be ...
1
vote
1answer
47 views

Searching a filename

How to search a file with a given String and currentTimestamp and if not found trigger a mail? For Ex-:I have to search a file whose filename would be like filename_05172015 and trigger a mail if not ...
0
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3answers
39 views

How can I add a line including single quotes to a file with sed [duplicate]

I want to append the following line to a text file with sed: gem 'forum2discourse' I've tried sed -i '$a gem \'forum2discourse\'' Gemfile but this drops me to a > prompt so I think I must be ...
6
votes
5answers
203 views

How to execute a bash command in all possible subdirectories?

Let's say my main directory is /home/test Under it i have lots of subdirectories and under subdirectories still a lots of them and so on. Example: /home/test /home/test/subdir1 ...
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0answers
41 views

How to rewrite the comand using I/O redirections?

Is there any way to rewrite the following command using only I/O redirections and not pipes ? ls -l | grep User | wc -l | tail -l
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4answers
92 views

Why . /home/Desktop is incorrect and ./Desktop is correct?

I'm learning about Linux, started yesterday. I have a question which I couldn't answer from my book or Google. What is the difference between ./ and / in the shell? I'm asking this because when I ...
2
votes
1answer
30 views

Reading keypresses in shell using trap and Unix signals

I am trying to grasp a fairly involved Unix shell (tested in bash) function that listens for keypresses. The full code can be found here. The part I am having trouble understanding is the purpose of ...
0
votes
0answers
25 views

Issues with Screen - Running Minecraft in a while loop through a screen session

So two days ago I changed my startup scripts for my minecraft server. Problem is, after about 3 hours, the screen for it that I was monitoring "mc" vanished and refuses to list when using -ls. The ...
0
votes
3answers
140 views

Can a command be executed without a shell?

I am developing a binary executable program command to execute programs and return the output into a text field. The parameters to the command involve the command itself as it would be typed on the ...
18
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5answers
543 views

Find files that a user can write, efficiently with minimal process creation

I am root. I would like to know whether a non-root user has write access to some files - thousands of them. How to do it efficiently while avoiding process creation?
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2answers
58 views

Can not execute command with root in a remote Linux host

I try to migrate shell code to Python fabric code. The issue I meets is that Python can not execute command with root in a remote Linux host. Could anyone meet this issue and figure it out? I am very ...
1
vote
1answer
39 views

Shell read script for sftp

I have this working: % cat read.sh !/bin/sh file=list.txt while read line do echo "$line" cut -d' ' -f27 | sed -n '$p' > file2 done < "$file" % cat list.txt sftp> #!/bin/sh sftp> ...
4
votes
5answers
89 views

command which works like ~ (tilde) symbol to represent some directory

cd ~/scripts. This will go into scripts directory in my home. Similar to this, I want some "alias" kind of setting, which will allow me to enter some other directory so that, cd xxx/mywork -> will ...
0
votes
1answer
34 views

Take output field data string into variable

I want to grep for some specific lines from a log file, and then capture a specific part of that output in a variable and use it in other commands. The grep command I have is the following, where $1 ...
2
votes
1answer
39 views

xargs not prompting after each line

I want to know the size of all the data files in my directory. I tried using the following command. The file names all start with data_. find . -name 'data_*' -type f | xargs ls -sh -n1 -p I do ...
3
votes
3answers
46 views

How can I list every port serving a web page

I have a number of servers, all with various HTTP(S) services accessible on a variety of ports. It's incredibly difficult to keep track of which service is available under which host and what port. ...
1
vote
4answers
217 views

Wildcards for filepaths aren't working in grep [duplicate]

I need to grep words like these: ABC-DEF AB2-DEF AB3-DEF AB-DEF So I was trying: grep AB*-DEF grep -w -AB*-DEF grep -w AB*DEF But neither of them are working. Please help.
1
vote
1answer
32 views

Restrict ssh access per user based on conditions

Is there a way to restrict a user to only use ssh to connect via SFTP, but disallow that same user to login to a secure shell terminal? I only want the user to have the ability to connect by an SFTP ...
1
vote
2answers
27 views

Separate bashrc file for ssh sessions to avoid Unison Errors

Recently my Unison started throwing up some strange error whenever I tried to sync between my laptop and my PC. I realized that I had added a line in bashrc that would print my pending tasks whenever ...
1
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2answers
46 views

Aliasing using for or while loop in .bashrc

Can I use a for or while loop when I have similar pattern in the aliases that I put in my .bashrc file? For example, I have: alias c0='ssh computer-1-0' alias c1='ssh computer-1-1' alias c2='ssh ...
0
votes
3answers
114 views

How to loop through lines in a file which contains * in each line

I have a file that contains about 800 lines. All the lines contains 1 * character in it. I need to loop through the lines in the file so I used the following simple for loop for i in $(cat ...
-1
votes
1answer
29 views

How can I execute and export in a single shellscript

I have two shell scripts. $ cat java_alternative_7 #!/bin/sh sudo update-java-alternatives -s java-7-oracle $ cat java_home_7 #!/bin/sh export JAVA_HOME=/usr/lib/jvm/java-7-oracle It's simple that ...
2
votes
1answer
31 views

Can not access my external hard drive.

I am fairly new to Linux and have been trying to move some files around with terminal on my external hard drive but I can't seem to get it to work. I am using a generic external hard drive with a ext4 ...
4
votes
3answers
50 views

Why can't I open a shell from a pipelined process?

I've condensed my problem into the following code: #include <stdio.h> int main(){ char buffer[256]; printf("Enter input: "); scanf("%s", buffer); system("/bin/sh"); ...
3
votes
1answer
77 views

difference between /bin/bash and “.”

Env: Ubuntu 14.04 I have a file called bc on my home folder. The whole content of the file is func() { local a b=() echo $0 } func Note there's no #!/bin/bash at the beginning. Then, if I ...
2
votes
2answers
58 views

Reliably identifying the path to the directory containing the running script

There are plenty of answers in SO to address this question: Can a Bash script tell what directory it's stored in? Unix shell script to find out which directory the script resides? And there are a ...
10
votes
1answer
150 views

Track certain parameters on some command

Let's say that I have a command git branch (always with a couple of words) for example. What I want is to keep track of when this command is executed with arguments. For example, if I execute the ...
0
votes
1answer
20 views

A generic cron wrapper that records all output

I am hoping to write a cron wrapper that records all output in a folder $CRON_LOG_DIR. It would be used as, e.g., follows: * * * * * $CRON_WRAPPER "<job name>" "command" which would record ...
1
vote
1answer
62 views

Using MPI with a .sh script?

I am a beginner with Unix and MPI. I have a runPR.sh script as below DIR=/directory/buildagain/bin/Project FILELIST=$1 while read FILE do echo "Processing ${FILE}..." ./makeInp.sh ...
2
votes
2answers
42 views

Replace between patterns that start and end in different lines

I have a file with the following format: Whatever1 Whatever2 Whatever3 binaries=( text1 bin2 ohhh3 ) Whatever4 Whatever5 Whatever6 I need to replace whatever inside lines binaries=( and ) with a ...
0
votes
1answer
77 views

Ubuntu changing shell on me

This Ubuntu machine is showing errors when I start a new terminal. The problem is this: When bash completion is sourced (. /usr/share/bash-completion/bash_completion) the shell taking place is not ...
5
votes
2answers
133 views

scp command behaves differently when used with expect utility

expect -c 'spawn scp -C -o CompressionLevel=9 ~/partFiles/* abc@10.200.4.15:/export/home/abc/; sleep 10; expect password; send "secretPassword\n";interact' throws - ~/partFiles/*: No such file or ...
2
votes
1answer
64 views

How to replace “&” with “&amp;” except when already part of an XML entity?

I have a file (xml) with many &amp;/&lt;/&gt;/etc, but sometimes also some & characters by themselves. I want to change this symbol to &amp; without replacing the others. cat ...
1
vote
1answer
50 views

Pattern matching inside awk

I intend to modify the output of ls -la to display the output of file command. The below command works well for the purpose find /opt -type f | xargs ls -let | awk 'BEGIN { OFS="\t" } { sprintf("file ...
1
vote
2answers
76 views

bash - Why does type -a execute “$(printf 'a')” and is it possible to get back the original alias? [duplicate]

After i ask this question 2 days ago, i decided to make this alias in my ~/.bashrc: alias catvu="LC_ALL=C sed \"$(printf 's/[^\t -\176\200-\377]/^&/g')\"|LC_ALL=C tr '\0-\10\13-\37\177' ...
1
vote
1answer
24 views

.bash_logout or .zlogout isn't parsed when autostarting xserver directly after login on console

I made a line: [[ -z $DISPLAY && $XDG_VTNR -le 4 ]] && exec startx (right out of the Arch Wiki) at the end of .xinitrc to start the Xserver right after login on console. Whenever ...
1
vote
1answer
20 views

When not started from a terminal, Emacs does NOT pick up the SSH_AUTH_SOCK environment variable

When I don't start it from a terminal, Emacs 24.5.1 (compiled from source) doesn't pick up my environment variables. In particular, to "import" the environment variables from shell, I have in my ...
1
vote
1answer
49 views

Automate input to the shell of a program

These days many programs like mongodb, docker etc, have there own shell i.e., if you type docker -i it opens an interactive shell (similarly with mongo and other programs). Is there a way to automate ...
1
vote
1answer
32 views

Writing a tab completion script for bash

I made a shell script that reads input from user and kills a process. But in bash if the user presses Tab key then bash suggests some keyword or file names. My script however doesn't suggest anything. ...
2
votes
3answers
268 views

“ sudo: source: command not found”

$ source /etc/environment $ sudo source /etc/environment [sudo] password for t: sudo: source: command not found It seems that a different shell than bash is run to execute source ...
0
votes
1answer
32 views

csh: Terminal inherits environment variables from an unknown location

I'm on a shared machine running CentOS 5.10 that I log onto using VNC from Windows 7. Our default and official shell is csh. Every time I open a new terminal, I have three particular environment ...
1
vote
2answers
41 views

Show output of a command run inside screen if it exits with errors

I am using the screen command for starting server running in foreground. But in case there is an error when starting server I am not able to see the output of command. I have to run it again without ...
1
vote
2answers
38 views

Copy line in file if we know the pattern [closed]

We have a file which has 10 lines, and I know that some line has text QWERTY. How can I manipulate the file so that it copies that line and paste it. The output is similar to that yy and p command ...
2
votes
2answers
63 views

Weird behaviour when setting environment variables with .bash_profile: only last export works properly

I am trying to export some environment variables in Unix using the .bash_profile It reads now like this: export PATH=${PATH}:/usr/local/cuda-6.0/bin/ export ...