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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3
votes
1answer
252 views

How can I make stdin always get consumed?

Some programs do not read from stdin (such as dmesg or adb logcat). I usually press Return a few times to provide a separation between log lines. When I interrupt the command directly in the shell, ...
3
votes
2answers
124 views

OS X: how to keep the computer from sleeping during a http connection

An application I use downloads data from a specific server, and I need it to sleep after the download has finished and the socket is closed. However downloads take place at random days, the app that ...
0
votes
1answer
1k views

Occasional error from bash on AIX: Interrupted system call

I am experiencing problems with process substitution in bash on AIX It happens very rarely, apparently only when the server is loaded. An example error message is: line 9: /tmp//sh-np-7841523: ...
2
votes
2answers
1k views

How to invoke a shell built-in explicitly?

I want to customize the functionality of cd command as per my needs. I define following function - function cd () { cd "$@" && pushd "$@"; } The intent of this function is to automatically ...
2
votes
1answer
3k views

locale-dependent bash script: How to properly ensure locale?

I went through a strange bug in a bash script which is on another machine, accessed via ssh (or other ssh like clients). It was basically a menu, in particular showing IP address(es) of the machine ...
3
votes
1answer
151 views

script to remember dir and always cd to it instead of the root dir

How can write a script to change to a given directory but also remember it so that when you do cd it always changes to that directory ? #!/bin/bash setdir() { cd $1 # remember the directory ...
1
vote
2answers
267 views

Ensure /etc/export contains rule using bash

What's a working example of modifying /etc/export using bash? Example: I want to ensure the following rule is present and valid: /export/home 2400:123::/32(rw,no_root_squash) And it should: Add ...
3
votes
1answer
146 views

Navigating the CLI: Go back N words

I'm a Vim user, so I'm learning Emacs commands for use in the Bash CLI. I know that on my systems I can use Vim-keybindings in Bash but I'd like to learn how to use it effectively in its default ...
5
votes
2answers
2k views

Get the PID of file creation

I am writing a bash script that creates 5 files with the extension ".P" and write a line of "something" into them. "P" represents a number and it's the PID of the process that creates the file. How ...
12
votes
2answers
4k views

find and remove duplicates in a directory

I have a directory with multiple img files and some of them are identical but they all have different names. I need to remove duplicates but with no external tools only with a bash script. I'm a ...
3
votes
2answers
171 views

Is it possible to transfer the history of commands from one system to another?

I am going to have all my data transferred to a new PC. Is it possible to transfer the command history of the previous Linux to the new system as well? So that when I type the history command, I get ...
0
votes
1answer
87 views

What's meaning the of a pair of parentheses after a string literal?

I accidentally input the the following command into the Bash terminal: exit() And the Bash keeps read the next line until I input a string literal and Bash gives the error of "-bash: syntax error ...
3
votes
1answer
205 views

code review: automatic completion for bash aliases

I was reading How do I get bash completion for command aliases? and I thought, that the answer by Shawn J. Goff needed a little something: less user setup so I wrote a little script that is intended ...
2
votes
1answer
120 views

how to record different values of a “flag” file

I have a black-box system that periodically updates a single-line "flag" file. This single-line file takes, over the course of the system's life various different values, corresponding to the states ...
3
votes
2answers
8k views

bash: insert character at specified position in file

Lets say I have following file word1 something blabla anotherword somethingelse asdf yetanother else 123 For each line, I need to put a comment infront of the ...
1
vote
1answer
38 views

ssh: define group of servers [duplicate]

I am using a script to connect to multiple servers. At the moment, I am using something like: for SERVER in server1 server2 server3 ; do ssh $SERVER "my-command" ; done I have to specify the (many) ...
1
vote
3answers
469 views

Creating a file counter that includes hidden files

As part of a programming assignment I need to create a piece of code that will count the number of files and directories (including hidden) recursively. I'm not allowed to use the commands -R, find or ...
2
votes
2answers
150 views

stripping out the last two [end] with sed?

I'm working on a script that improves the fluxbox 'menu', and my script has this line: sed -i 's/\[end]//g' ~/.fluxbox/menu;sed -i '/^\s*$/d' ~/.fluxbox/menu but this has the unfortunate effect of ...
3
votes
2answers
8k views

What is “Exit 2” from finished background job status?

I have an exercise to put in a file some data (*conf from some directories) and need to do this in background. I did it and I am wondering what is the meaning of output messages: [A@localhost tests]$ ...
3
votes
4answers
529 views

Bash: For loop with binary range keeping control value binary

Let's say I have two bash variables that contain binary values: a=0011 # decimal 3 b=1000 # decimal 8 Is there a way I can loop through all the possible values between $a and $b keeping it binary? ...
0
votes
2answers
614 views

Test if number from range <0,infinity)

I have a problem If [[ * ]] then continue else exit 1 fi I want to test that the argument to my switch (for example -d 3) is a valid positive decimal integer number (a sequence of one or more of ...
3
votes
2answers
74k views

mail: send email with attachment from commandline [duplicate]

I know how to send an email from command line (script) echo "body" | mail -s "subject" my@email.com Is it possible to send attachments from commandline (script) as well? I am using heirloom-mailx ...
1
vote
1answer
337 views

exported variable disappears when I open a new terminal

I type this: export JAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk so that I can access that directory by typing cd $JAVA_HOME but every time I close and open the terminal I have to do this again and ...
1
vote
1answer
131 views

Trouble getting menu to work

Currently I’m trying to get a menu working for my Into to Unix class. The problem I’m getting right now is that when I input something into the script my input appears instead of the script responding ...
8
votes
2answers
751 views

How do I columnate a list of items with minimal width?

How do I columnate any uncollumnated input like ls does? ls is creating an optimized table with minimum width for each row, for example: ls 2 dsao file with space with 5 e g ...
-1
votes
1answer
209 views

find not working right

if [[ "$1" == "" ]] then leftarray=($(find . -type l -printf "%p\n" 2>/dev/null)) rightarray=($(find . -type l -printf "%l\n" 2>/dev/null)) for var in "${rightarray[@]}" do ...
2
votes
3answers
740 views

how to pipe find's output into another find

In searching how to make find sort the files it finds based on modification time I found this answer which provides the following incantation: find . -type f -printf '%T@ %p\n' | sort -k 1nr | sed ...
8
votes
1answer
818 views

Why doesn't the process substitution <() work with ssh -F

I have some vagrant virtual machines. To log into them I issue the vagrant ssh command. I want to log into them using regular ssh command. The vagrant ssh-config outputs the suitable config file $ ...
4
votes
4answers
605 views

Remove all files except for last file of each month

Consider a directory with MySQL backup files with timestamps as part of the filename: -rw-rw-r-- 1 ubuntu ubuntu 35856184 Nov 16 16:00 db_2013-11-16_1600.sql -rw-rw-r-- 1 ubuntu ubuntu 35856915 Nov ...
3
votes
3answers
82 views

Script is stuck saying 1 response with 2 available: Math related

I have a script that tells the user the square footage of 2 rooms based on user input. I think I have that part done right. The problem I have is that I need to have the script say which room is ...
0
votes
2answers
706 views

Count occurrences of line in multiple files

I have log files that I need to grep and count the number of occurrences of a specific line. Issue is that I must start at a specific line of the first file and only count occurrences after that ...
2
votes
3answers
573 views

How can I tell echo/printf in Bash to swallow escape codes, based on a condition?

I have a Bash script that is being run interactively and as a cron job. When run interactively it outputs colored text on the terminal. However, when run in cron it doesn't have a terminal and ...
5
votes
2answers
250 views

How to report time and other information on all bash commands? [duplicate]

Most of the things I run in the terminal take a long time to compute and I would like to have bash output a time report at the end of every command entered into the terminal. Is there something I can ...
2
votes
1answer
145 views

Check for existence of files prior to acting on them

In one of my processes I check for existence of files older than 31 days, and then do stuff with them. find /my/directory/*txt -mtime +31 -exec ls -l {} \; All this is well and fine if files are ...
4
votes
1answer
385 views

bash_completion for initscripts

I have writen my own initscript /etc/init.d/myscript. I can start and stop my script with the service command service myscript start service myscript stop When I type service <TAB>, ...
3
votes
3answers
970 views

Correctly parse arguments in script behaving like a shell called through SSH

I have a server with a very limited used whom I want to be able to run two very specific (and custom) instructions through SSH. In order to do that, I have set the shell for that limited user to be a ...
5
votes
2answers
9k views

Bash globbing and argument passing

I have the following simplified bash script #!/bin/bash files=("$@") if [ "X$files" = "X" ]; then files=$HOME/print/*.pdf; fi for file in "${files[@]}"; do ls "$file"; done If I pass ...
4
votes
5answers
6k views

Bash: What is the use of type (Bash builtins)?

I came across a command in Bash script in which I found: find /var/log/abcd -type f The above command was in context of cleaning the log files. I know what find does. After having seen -type f, I ...
6
votes
3answers
29k views

How do I echo just 1 column of output from ls command?

Lets say when I do ls command the output is: file1 file2 file3 file4 Is it possible to display only a certain column of output, in this case file2? I have tried the following with no success: echo ...
2
votes
2answers
434 views

How to load .bashrc from “bash -c”

Trying to run a function defined in my .bashrc using "bash -c ". I end up with the error "command not found". How do I get "bash -c" to load my init file?
1
vote
2answers
1k views

.bashrc execute command after “/bin/bash --login”

I have this alias in my .bashrc: alias s='cd ~/Documents/projects/s && /bin/bash --login && rvm use ruby-1.9' How can I execute the right part after it enters login shell (/bin/bash ...
3
votes
1answer
300 views

command not found handle doesn't work for url

I'm trying to setup the command_not_found_handle for URL links, %> command_not_found_handle() { echo "OK"; } %> aaaaa OK %> http://www.google.com bash: http://www.google.com: No such file or ...
0
votes
2answers
626 views

Two or more yes/no questions in a script?

I'm writing a bash script which has a "yes/no" question in it, but now I want to have another yes/no question in it. The script can only cope with one yes/no, so how can I have two, or more, yes/no ...
0
votes
1answer
328 views

Rename multiple files removing last characters and renumbering

I have a photo directory with hundreds of files named in the format: 2013-08-02 19.21.27.jpg I wish to keep the first 10 characters (date) and append "-001", etc. being consecutive for each date. ...
1
vote
1answer
225 views

Create Relative Symlink Inside Relative Symlink

I've been browsing for a minute now trying to find a way to create a relative symlink inside a relative symlink, and what I mean by that is this... I have my CakePHP Templates Skeleton as a symlink ...
1
vote
3answers
310 views

Filtering a result from a command

I am having trouble writing a little program; when I run the following command from my program: gsettings get org.gnome.desktop.background picture-uri I get: ...
1
vote
2answers
254 views

Using globbing/wildcards when Opening Files from Terminal

I have a folder A. Inside the folder, there are some files a,b,c,d and there is a subfolder, B, containing files e,f,g. Suppose I want to open files a,b,c,d: then I just type xdg-open *. However, ...
16
votes
3answers
16k views

Generate File of a certain size?

I'd like to generate a file with the name example.file. I could use touch example.file but I want the file to be exactly 24MB in size. I already checked the manpage of touch, but there is no ...
1
vote
2answers
344 views

What does this regex mean?

I was working on the conversion of Unix newline to Windows newline. I tried to unix2dos but it gave me some binary error, so I looked it up and stumbled upon this regex sed 's/$'"/`echo \\\r`/" ...
1
vote
1answer
1k views

getopts - how to avoid read next $OPTARG as argument?

Just started use getopts and found one problem... For example - have a script with: while getopts "h:loav" opt; do case $opt in h) h=$OPTARG echo $h ;; But whet I run it: $ ./ftpclean.sh -h ...