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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4
votes
2answers
226 views

Inconsistencies between redirecting input from file, here docs, and here strings

Why is this inconsistent? I would expect here docs and here strings to be functionally equivalent to redirecting input from a file. $ bash --version GNU bash, version 4.1.2(1)-release ...
6
votes
2answers
173 views

Can I use variables inside {} expansion without `eval`?

Can I use variables inside {} expansion without appealing to eval? If so, how? This doesn't work: $ touch 1.foo 1.bar $ ls 1.{foo,bar} 1.bar 1.foo $ extensions=foo,bar $ ls 1.{$extensions} ls: ...
1
vote
1answer
572 views

bash control statment for when an option flag is used

I trying to make control statement to check on a option flag is used or not? For -o output.file if is used I would like to make equal to variable OUTPUTSUM = OUTPUTFILE and if there no -o option use ...
4
votes
1answer
154 views

Is there a way to cat files as they are created? [duplicate]

Unlike the answer to this question (Can a bash script be hooked to a file?) I want to be able to see content of files that haven't been created yet as or after they are created. I don't know when ...
1
vote
1answer
164 views

Debian, nonroot, cron, bash script and rebooting at specific time

As nonroot user, how can I schedule a reboot every day at 4:30am? 30 04 * * * /home/user/scripts/reboot.sh As a nonroot normal user, I'm sure the system won't allow me to use the reboot command. ...
1
vote
1answer
82 views

Who is setting http_proxy?

On an Ubuntu system with bash as the default shell for the interested user, the http_proxy environment variable is set to a specific value in a fresh GNOME Terminal. The .bashrc file for this user ...
0
votes
1answer
375 views

execute commands as parameters in a login shell

We started using a new integration and production pipeline called GO. To execute a bash script there, the convenient way is to use the bash command instead of executing the script directly. For that ...
6
votes
3answers
268 views

Is it possible to use variables in count braces in Bash?

I'm searching for a solution to a Bash 4 problem I have. Bash 4 is able to iterate with leading zeros. For the line: for i in {001..005}; do echo -n $i" ";done;echo the output is 001 002 003 004 ...
5
votes
4answers
1k views

How to quote a string containing dollar sign $ and single quote '?

My directory's name contains a $ and ', for example :~$ export DIR=\$my\'dir :~$ sh -c "ls $DIR" How can I run above command without $my being expanded? I know the single quote doesn't work since ...
66
votes
2answers
95k views

There are stopped jobs (on bash exit)

I get the message There are stopped jobs. when i try to exit a bash shell sometimes. Here is a reproducible scenario in python 2.x: ctrl+c is handled by the interpreter as an exception. ctrl+z ...
3
votes
1answer
41 views

Script to dripfeed files

I need to write a script that will check a directory for a given file type, say *.mov, and move up to, say, 50GB worth into another directory. The purpose being that we have a huge bunch of files that ...
26
votes
6answers
11k views

where is `cd` located? [duplicate]

In a bash sub shell I get the following error when running cd sudo: cd: command not found This is expected because I don't have a path. Usually to work around this I just provide the full path like ...
2
votes
4answers
2k views

regex matching with “locate”

I'm trying to use the locate command to find files in my home folder, however whenever I try and run this I get no results: locate -i -l 4 --regexp '^\/home\/jack\/[A-Za-z0-9\/\ ]*(My.)*$' I've ...
4
votes
2answers
1k views

Privileged mode in bash

I've used bash for years but I 've stuck with the"privileged mode" that it can be configure with the set command. For example: set -p I've read the bash man page but it's somewhat obscure. For ...
2
votes
4answers
5k views

command to mass rename files according to pattern [closed]

I have a lot of files in a directory that are named as follows ID_OTHER_STUFF.txt I'd like to rename them all to ID.txt. This isn't a duplicate because I don't know how to specify this pattern.
1
vote
3answers
93 views

Substituting number into file name in bash [closed]

I'm trying to download multiple files such as: www.example.com/v1/file.txt www.example.com/v2/file.txt www.example.com/v3/file.txt ... The following command doesn't work, as it actually looks for a ...
8
votes
6answers
1k views

Semi-asynchronous pipe

Assume I have the following pipe: a | b | c | d How can I wait for the completion of c (or b) in sh or bash? This means that script d can start any time (and does not need to be waited for) but ...
4
votes
1answer
539 views

Why do piping and redirection work differently with here documents?

Combining a redirect with a here document seems logical enough: $ bash > foo <<EOF echo Hello EOF $ less foo Hello But with a pipe it behaves differently: $ bash | tee foo <<EOF ...
6
votes
4answers
1k views

Using sed to add a URL to the start of every line

I have the URL (see below) of a certain web page that lists many different versions of a software package. URL=http://ftp.gnu.org/gnu/wget/ The following one-liner gets me the latest version tar ...
0
votes
1answer
1k views

how I can generate mac address increamental like 00:00:00:00:01 00:00:00:00:02

how I can generate mac address incremental like 00:00:00:00:01 00:00:00:00:02
2
votes
2answers
63 views

join sed output

I'm looking to somehow pass the output of the following command: $ sed -n '5p' file-A into $ sed '5 c\ > "string extracted from previous sed command" file-B So basically, I want to replace ...
21
votes
2answers
2k views

^x^y unix trick for all instances in last command?

One of my favorite Unix tricks is ^x^y, which will take the last command and replace the first instance of "x" with "y". However, I'm wondering if a similar trick works to replace all instances of "x" ...
5
votes
2answers
14k views

bash script error: source: not found

I must be missing a fundamental understanding about sourcing files in bash. I've tried the different approaches that seem like they should work, but I still get this error source: not found. In my ...
14
votes
7answers
6k views

How to detect the desktop environment in a bash script?

I am writing a bash script that needs to know which desktop environment (XFCE, Unity, KDE, LXDE, Mate, Cinnamon, GNOME2, GNOME3,... ) is running. How can I obtain that information?
1
vote
0answers
59 views

manipulate a Drush “internal” variable

I want to modify a variable (preferably in a Bash Script format) because my PHP environment requires a port number. To show a URL in Drush containing a token that logs you in as user 1 (without a ...
1
vote
1answer
263 views

What version of bash am I running

I tried to change default bash on OS X Mavericks, Installed new bash trough brew, run chsh -s /usr/local/bin/bash, went to "Users and group" made sure that Login shell for my login points to the ...
-1
votes
2answers
2k views

List the file permissions of only the current directory [duplicate]

ls -la . will show this in it: insgesamt 1312 drwxrwxr-x 6 ruben rubo77 4096 Feb 23 06:20 . drwxrwxr-x 23 ruben rubo77 4096 Feb 6 21:48 .. ... But it will show the whole content of the ...
0
votes
1answer
174 views

Is it a bad idea to keep scripts in /root? [closed]

Is it a bad idea to keep scripts in /root? Simple bash scripts that have the following permissions: -rw-r--r-- They execute fine when ran as root, but is this bad practice? It's a multi-user system, ...
1
vote
1answer
531 views

How to control buffering of pipes in bash scripts?

I need my script to be executed with stdbuf -i0 -o0 -e0 otherwise user will wonder why there is no output (becuase of pipe buffer). How can I acheive it? #!/usr/bin/stdbuf -i0 -o0 -e0 /bin/bash ...
3
votes
1answer
129 views

Assignment to variables

I was trying to devise a solution to a different question asked on the site and came across this curious issue. Here is the set of commands that I issued: $ foo=82a9948422 $ echo $foo 82a9948422 $ ...
8
votes
2answers
2k views

Why did BASH print “bash: cd: write error: Success”?

I noticed this several times today. If I type cd ../Directory to change to another directory, it prints "bash: cd: write error: Success". I can't determine what other previous commands might be ...
3
votes
2answers
3k views

Read non-bash variables from a file into bash script

My bash script needs to read the variables from a text file that contains hundreds of variables, most of which conform to standard bash variable syntax (e.g., VAR1=VALUE1). However, a few lines in ...
3
votes
2answers
766 views

Moving large numbers of files and directories to a different directory

I'm trying to move the following move a large number of files that exist in the following structure to a /mnt/originals but I need to maintain the structure at the same time. I know cp would be a ...
5
votes
2answers
882 views

ls for cut -f string not working

I have a problem with feeding cut output to ls. This doesn't work: rep="S1_1000,0000-00-00c,0000-00-00d,0000-00-00e" ls tab_yeast/{`echo $rep | cut -f2- -d','`}*.tab.gz ls: cannot access ...
14
votes
4answers
8k views

What does a bash sequence '\033[999D' mean and where is it explained?

I have come across bash sequences such as \033[999D and \033[2K\r which are used to do some manipulation on a printout on a terminal. But what do these sequences mean? Where can I find a list/summary ...
6
votes
5answers
18k views

parse json using python

I have a JSON file members.json as below. { "took": 670, "timed_out": false, "_shards": { "total": 8, "successful": 8, "failed": 0 }, "hits": { "total": 74, ...
2
votes
1answer
962 views

Copy files based on date/time from subset of directories

I'm teaching a class where (~80) students are submitting assignments that I can access via webdav, organized by student in directories named by their unique identifier. The students are split into ...
7
votes
3answers
10k views

reliable return code of background process

Let's assume the following piece of bash code: foo > logfile 2>&1 & foo_pid=$! while ps -p$foo_pid do ping -c 1 localhost done wait $foo_pid if [[ $? == 0 ]] then echo "foo ...
5
votes
2answers
9k views

Interactively concatenate video files

How to concatenate (join) multiple MP4 video files into one file interactively? There are a lot of programs that do this for two files from the command line. For instance: ffmpeg avconv MP4Box ...
6
votes
1answer
3k views

Meaning of bash -i >& /dev/tcp/HOST/PORT 0>&1?

I tried this bash -i >& /dev/tcp/HOST/PORT 0>&1, but it does not seem to work behind firewall. What does this code actually do, which ports are forwarded and could it work behind ...
1
vote
1answer
251 views

Program installed to `/home/username/bin` and added to path… not launching [duplicate]

I just installed newer versions of grep and vim to my local ~/bin directory. I have the path added via PATH=$PATH:$HOME/bin in my .bash_profile. When I try to run either, the version installed in ...
0
votes
1answer
135 views

Prompting when redirecting content of script to remote machine

I have simple script: #!/bin/bash while getopts ":u:" opt; do case $opt in u) USER="${OPTARG}" ;; \?) echo "Unknown flag has been used: -$OPTARG" >&2 exit 1 ...
3
votes
1answer
1k views

variable expansion within command substitution over SSH bash 4.X

I want to do this ssh ${w100user}@web100 'ls -l "$(grep "${1}" /etc/pure-ftpd/pureftpd.passwd|cut -d':' -f6)"' Which obviously performs an ssh session to server web100 as w100user and then greps ...
3
votes
2answers
179 views

Command in variable one are affecting output of other variable when displayed together in UNIX

I am having two file naming Extra_info and Class_info Class_info contains data : stuId stuName stuClass S01 jagdeep First S02 harsh First S03 Roop Second S04 Kali Third ...
8
votes
3answers
2k views

Why does bash have a HISTCONTROL=ignorespace option?

Or to phrase it differently, why would you want to prevent commands from being written to the bash history? (Inspired by a related question.)
1
vote
1answer
1k views

Split screen just like Windows or Unity do

I'm looking in Debian wheezy for a way to split screen in two windows just like you can do in Ubuntu or Windows7/8. I mean I'm used to select a window and push windowskey+left and select another one ...
20
votes
1answer
1k views

Why is bash not storing commands that start with spaces?

If I perform a sequence of commands like: $ ls $ grep abc file.txt and then use the up arrow key to get the previous one, the terminal will show the last cmd (which is the grep here) But if I do ...
0
votes
1answer
42 views

Why dircolors don't return enything for bash called from php

I have this code in php: header("Content-Type: text/plain"); exec("/bin/bash -c 'dircolors -b'", $result); echo implode("\n", $result); but it return LS_COLORS=''; export LS_COLORS Why I'm not ...
1
vote
0answers
9 views

Bash in php exec don't color png and mp3 files on Linux [duplicate]

I have code like this: header("Content-Type: text/plain"); exec("/bin/bash -c 'ls --color=always'", $result); echo implode("\n", $result); and I've got result: Makefile README Yann Tiersen - ...
3
votes
2answers
6k views

delete old log files except the last one (alphanumerically sorted)

I have a number of log files in the form: log.2014-02-19-10_24_22 I.e. log.YYYY-MM-DD-H24_MI_SS The date that's part of the log file's name is when the log file was first created. So at any given ...