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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43 views

How to password protect a file? [on hold]

I have the script called Linux.sh. I want it to be executable by everyone on mobaxterm, but others should not be able to edit the script. Is there any way to password protect the script.
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2answers
17 views

How to search parenthesis by ack

I want to search for a parentheis ( using ack, but neither using ( nor \( worked. The first one ("(") is recognized as a multiple line command. The second one ("\(") is treated as an invalid regular ...
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1answer
15 views

find files with two types of extensions last modified over 30 days ago

I want to find all the files in a directory that have not been modified for at least 30 days and end in .xml or .out. This is my attempt to cobble together a couple of references to build the right ...
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3answers
25 views

Change Multiple (Including No) File Extensions

If I have a directory of files, where some files have an extension like .html and some files have no extension, how do I change them all to, e.g. .txt?
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2answers
27 views

Why is a variable passed to the su command, but not an array from the same scope?

In the example below, why does $var get passed to the su in the start function, but not the array modules ? #!/bin/bash var=cat modules=( one two three four ) start() { su gleventh -c "for i in ...
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1answer
51 views

how to locate a name-not-specified file in bash? [on hold]

I have a bash like this to easily upload a file to my server: FILE=../"$1"/1.txt scp 1.txt remoteserver #upload the file to a remote server. The $1 is for input directory and I have a lot of ...
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1answer
19 views

Which way is safer to read data from /sys

I am attempting to write a program that will monitor the temperature of various hardware components. The language I chose for it is Java. Now there are two ways I could read the temperatures: a) Do ...
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4answers
46 views

Completely buffer command output before piping to another command?

Is there a way to only execute a command after another is done without a temp file? I have one longer running command and another command that formats the output and sends it to a HTTP server using ...
0
votes
5answers
142 views

How to get current working directory? [duplicate]

I want to have a script that takes the current working directory to a variable. The section that needs the directory is like this dir = pwd. It just prints pwd how do I get the current working ...
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2answers
42 views

Why would the prompt get overwritten?

p_ash-3.2$ cp some_file1234.html /some/loc/ation/ofthe/some_file1234.html.html_Backu Have been seeing this intermittent issue with the command-line, while typing longer lines as part of any command, ...
14
votes
2answers
695 views

Renaming the current directory from a shell - possible?

Is it possible to rename the current working directory from within a shell (Bash in my particular case)? If I attempt to do this the straightforward way, I end up with an error: ...
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8answers
29k views

List only regular files (but not directories) in current directory

I can use ls -ld */ to list all the directory entries in the current directory. Is there a similarly easy way to just list all the regular files in the current directory? I know I can use find find . ...
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1answer
23 views

remove lines where a field's value is less than or equal to 3 - sed or awk?

I need to remove every line that has a value of 2 or less in the 8th field (column). My data looks like this: 12-31 Airport 189 379 41 49.70946503 -124.91377258 2 2880 30.8 01-01 ...
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0answers
23 views

convert from one memory format to another and find the difference between them

Using shell scripting, how can I convert from one memory format to another and find the difference between them? I want to compare current rate and previous memory rate (Where we need to compare ...
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votes
0answers
20 views

print character in specific rows and columns [on hold]

I have one file F1 having data Column 1 will represent character and column 2 represent multipliers (number of time a character suppose to be repeat). file 1 as input: A 2 B 4 C 4 D 6 ...
1
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1answer
30 views

Specify the type of field to modify in a file

I have a list of clients, "code", "name", "location", "etc" and I want to make a function that asks the employee to give the client's code and then the field he/she wants to change. For example, ...
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1answer
42 views

loop through multiple folders and perform commands then write to file

I have 10 folders that I want to loop through while executing the following command: awk 'FNR > 1' *.csv | sort -sk 1,2 | sort -sk 3,3 > ${f}_appended.dat With a for loop wrapper, like ...
2
votes
3answers
45 views

Calculate date difference between Last modified date of a file and NOW using shell script

I am trying to calculate the time elapsed since the log file was last updated. I guess following commands will be used lastUpdate=$(date -r myLogFile.log) now=$(date) How can I subtract them and ...
2
votes
3answers
41 views

space check on unix machines

I am having space issues on 1 of the UNIX servers. I am executing the below command to check the space utilization. But this command is very slow and takes hours of time to give the result. du -sg * ...
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vote
1answer
48 views

Shell script runs diffrently based on working directory.

I have a script which runs differently based on current working directory. Basically it processes an .ini file and takes parameters from it and runs mysql backup. Script is running as root user. ...
3
votes
5answers
157 views

Pick the latest file based upon the sequence number given in the file name

I have a requirement, I have few files in a directory, I need to pick the oldest one for processing. For Exp: I have below files in /tmp directory: Sample_0000237826-001_xyz.dat ...
0
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0answers
9 views

sending NEDIT to background on launching

I have this problem - for opening nedit it will open in the foreground. Then either you open it using & ex- prompt> nedit & is there any way where I can open nedit directly in the ...
2
votes
2answers
1k views

Using sudoers to allow php to run command

I am trying to get my php page to run this command: shell_exec("sudo /home/xbian/433Utils/RPi_utils/codesend {$num}"); So I added this entry to my sudoers file with visudo: www-data ALL=NOPASSWD: ...
0
votes
1answer
20 views

Error with sed on MAC OS X invalid command u

Im french sorry in advance for my bad english... So i have an error on MAC OS X when im using sed sed -i '' '/user_pref("mail.identity.id1.reply_on_top", 1);/ a\ ...
0
votes
1answer
15 views

Having problem with mysql dbdump when password starts with special character

I am trying to take a db backup with a php file that is running from a cronjob. It was running fine when I tested with sample db. But when I used the actual db there was an error. I am using ...
52
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4answers
3k views

Why is `[` a shell builtin and `[[` a shell keyword?

As far as I know, [[ is an enhanced version of [, but I am confused when I see [[ as a keyword and [ being shown as a builtin. [root@server ~]# type [ [ is a shell builtin [root@server ~]# type [[ [[ ...
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2answers
35 views

What is difference between Power broker utility and sudo command?

I got a little clarity with the following answer on this Source Symark Power Broker is a commercial package. Sudo is an open source tool.
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1answer
38 views

Can you please tell me what is wrong in below script?

script : it is giving below error. please help me. basically i need to get email when memory exceeds some limit. error : ./vamsitest.sh: line 10: [: missing `]'   #! /bin/bash # Total memory ...
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2answers
406 views

Script to su -c into a screen is not working as intended

I'm working on a script that will allow me to load up a screen from a user via sudo and su -c. However, when I use it, it will just show the shell of the user: sudo su -c "script /dev/null; screen -r ...
4
votes
2answers
258 views

How to echo `single quote` when using single quote to wrap special characters in shell?

I'm reading shell tutorial today from http://www.tutorialspoint.com/unix/unix-quoting-mechanisms.htm In which it mentions: If a single quote appears within a string to be output, you should not ...
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0answers
32 views

delete non important characters from command output

the version command in my Linux machines display the following output version Red.Hat.OS. release..........5.5 APP.Release.............4.2.0.0-02 how to remove the middle "." dot character ...
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votes
4answers
628 views

Spaces next to pipes

I've seen history | grep blah and history |grep blah; and history|grep blah also works, though no one ever seems to use it. Is there any significance in the spaces (e.g. piping to/from different ...
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3answers
52 views

How to use password in shell scripting

I am writing a script which greps for for multiple files from 3 log files. One of the log file is created as superuser and every time it executes it prompts for password. How do I put it the same ...
0
votes
1answer
19 views

Unable to extract to specific directory

I am trying to extract to file to specific directory but it doesn't produce result Operating system : SunOS Command: zcat /export/home/tceng/Desktop/temp/3.tar.Z | tar -xf - -C ...
2
votes
1answer
30 views

Windowless xterm? (Faking a terminal for a process)

I'm fighting with a rather odd problem with Matlab. The startup script is located in /opt/matlab_2013b/bin and is called matlab. When I run it in terminal, it works fine. But I want to make a ...
10
votes
3answers
961 views

What's the difference between semicolon and double ampersand && [duplicate]

What is the difference between echo "Hello " ; echo "world" and echo "Hello " && echo "world" Both seems to run the two commands after each other.
3
votes
3answers
60 views

How to bump file timestamps by 3 months (for a directory tree)?

I am looking at the touch command line utility (on Linux), and from the examples I found in tutorials, I see how one can bump the access or modification timestamp to a specified time, the current ...
5
votes
3answers
180 views

Echoing stdin when running an ed(1) script

Given the following ed script, $ cat helloworld a hello world . ,n ,s,o,O,g ,n Q I would like to obtain somehow the interactive output $ ed a hello world . ,n 1 hello 2 world ,s,o,O,g ,n 1 ...
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1answer
39 views

When did bash quit exporting SHELL?

I upgraded a Debian box from stable to Jessie and I noticed that SHELL is no longer exported, so screen and similar programs start dash for subshells instead of bash. When was this change made and ...
0
votes
2answers
42 views

Gzip file but excluding some directories|files and also append current date

I'm looking for a way to create a .tar.gz file from a directory but I have some doubts. I'm know that the command for create the file is: tar -zcvf /path/to/compressed/file.tar.gz /path/to/compress ...
2
votes
1answer
43 views

attempting to put dynamic input data in a variable via cat method

I'm attempting to write a bash script that should be able to collect data from ttyS0 and put in a variable. I need to talk with a device on the serial line, that is a module able to receive AT ...
1
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2answers
69 views

use “read” command to pass lines as positional parameters to a shell script

The following file runs, but not doing anything, yet it does not error.... while read dates; do ./avg_hrly_all_final.sh ${dates}; done < ./dates_all.csv I have a list of dates in ...
6
votes
3answers
837 views

Best way to swap filenames

I need to swap filenames of two files (file and file_1). I'm using the following code for it. mv file .phfile mv file_1 file mv .phfile file This works but is very buggy, It sometimes even results ...
92
votes
3answers
23k views

What does “--” (double-dash) mean? (also known as “bare double dash”)

I have seen -- used in the compgen command. For example: compgen -W "foo bar baz" -- b What is the meaning of the --.
0
votes
1answer
25 views

explain this shell command with redirection and pipe

I can understand the statements like. bzip2 --version >/tmp/list_right 2>/tmp/list_error bzip2 --version >/tmp/list 2>&1 But I don't understand the statement: bzip2 --version ...
0
votes
1answer
1k views

How to execute Netscaler commands through a remote machine via SSH connection

I have been trying to execute some NetScaler commands like "bind" & "unbind" through a Linux Box via an SSH Connection. Now the Problem is, Manually we are able to enter & execute commands on ...
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0answers
38 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 ...
2
votes
3answers
3k views

How to escape a single quote? [duplicate]

This works fine: sed -i 's# @driver.find_element(:xpath, "//a\[contains(@href,##' temp_spec.rb against a source of @driver.find_element(:xpath, "//a[contains(@href,'change_district')]").click ...
1
vote
0answers
59 views

Sed regex printing into a file.txt

I'm connected to a MQTT stream, and I filter out the data by entering : mosquitto_sub -d -t +/# 2>&1 | sed -n "/PUBLISH/{s|.*\('.*',\).*|\1$(date),|;N;s/\n//;p}" into the Ubuntu terminal. ...
0
votes
1answer
31 views

looping through a file on 2 lines in shell

I have a file which looks like this: >a TCCACTCCACGC >b ACCTCCAG I want to loop through the file in such a way that it takes into account 2 lines at a time i.e >a and its sequence and then ...