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
2answers
4k views

find the single largest file

We host a share of size 4 TB. How efficient is it to find a file with highest size. Usually we use: du -ak | sort -k1 -bn | tail -1 and it is not easy to scan through a share of such huge size and ...
2
votes
1answer
743 views

bash not reading $TERMINFO on login (over SSH)

I have a OpenVZ Fedora 20 VPS that when I SSH into, my termcap file stored in $XDG_DATA_HOME/terminfo/x/xterm-termite, isn't being read, despite having TERMINFO=$XDG_DATA_HOME/terminfo set. If I ...
3
votes
5answers
6k views

Getting pid of bash script from itself

I have a bash script with doing lot of things called script.sh: #!/bin/bash #It #Is #Doing #Things Is there a way that I be able to get the proccess of script and then kill it after 5 minutes? ...
3
votes
1answer
267 views

Difference between “.” and “./” while setting the environment variables using export? [duplicate]

Please excuse me if I am not clear while asking questions. I will try my best to be very clear while asking questions. While learning Embedded Linux, we are setting an environment for our project. ...
0
votes
4answers
181 views

Applying different permissions to files vs. directories

Sunny answered the question above in this post, The answer was given as No need for scripts. // Directories: find . -type d -exec chmod XXX {} \; // Files: find . -type f -exec chmod ...
9
votes
2answers
3k views

Check bash/shell script dependencies

Is there a method/command to check for the dependencies of a bash script? In other words, a response to this question : Which libraries should a user install to run the script? I can do this ...
1
vote
2answers
2k views

Bad configuration option: ControlPersist while scp with control master?

I am using SCP with ControlMaster to copy the files but somehow I am getting this error back - command-line: line 0: Bad configuration option: ControlPersist command-line: line 0: Bad configuration ...
1
vote
2answers
130 views

Toggle/macro/xargs-like thing for shell variables

So I'm stuck doing a lot of cross-compiling and am typing stuff like this a lot FOO=bar command --some-args BAZ=qxt other-command --other-args But obviously the real shell variables are long and ...
1
vote
1answer
190 views

rsync parallel vs serial transmissions

Using Bash 4 and rsync on RHEL 6, are there any differences between the following methods? If so, which is more efficient, and what are the differences between these 3 methods: 1) rsync -avz ...
0
votes
1answer
346 views

Using trap with ERR: How do I send $?

In bash 4.x If I have: err_handler() { echo You received error $1|mail -s "script error" MAILTO } trap err_handler ERR how do I send the actual stderr output to the function when the trap is ...
2
votes
1answer
198 views

How do I eval two commands?

If I run this: echo "echo 'a'; echo 'b'" It produces a string which I can then run, and it works - echoes a\nb\n. However, this does not work: $(echo "echo 'a'; echo 'b'") Why not? It doesn't ...
15
votes
2answers
7k views

alias vs export for simple commands

For simple commands like less, is it better to make an alias or to export the options? Is there any benefit of one over the other? For example, if I want less to always use the -R option to show raw ...
9
votes
2answers
16k views

Test tar file integrity in bash

I have a bash script that creates a '.tar' file. Once the file is created, I would like to test its integrity and send an email to the root user if the integrity is bad. I know I would need to use ...
3
votes
0answers
69 views

Some puzzles of how to close file descriptors on sh or bash [duplicate]

Question 1. What will happen if we close a input file descriptor as if it is a output file descriptor? (or vice versa). For Example, $ exec 5<&2 $ exec 5>&- In my linux box, ...
8
votes
4answers
30k views

bash: /home/user/.ssh/authorized_keys: No such file or directory

Create a ssh key: $ ssh-keygen -t rsa –P "" Moving the key to authorized key: $ cat $HOME/.ssh/id_rsa.pub >> $HOME/.ssh/authorized_keys bash: /home/user/.ssh/authorized_keys: No such file ...
5
votes
1answer
234 views

bash_completion rule for resolving ip into hostnames

I am trying to create a bash_completion rule for my script rmpxe. This script takes <hostname> as its only argument. It then resolves this hostname into <ip_address> and removes the ...
2
votes
2answers
594 views

Killing background process in bash script when exiting the script

I have a script that tail a file while displaying a clock in the top right corner. I took the clock part from the internet, and it works ok. The entire script is something like (I simplified): while ...
1
vote
1answer
314 views

Search for pattern across multiple files and replace a sub-part in all occurences

I am helping a friend with her thesis written in LaTeX and I need a quick solution for a "search and replace". Using a terminal in Linux, how can I find the following pattern: \caption{*\cite{*}} ...
1
vote
1answer
256 views

observing script execution with monit script seems to ignore pipes

I want to have a bash command running in the background and being watched by monit. To get the PID of this process, I found this script on the web and I modified it to fit my commands: (named sdr.sh) ...
0
votes
2answers
117 views

find action not working for specific search [duplicate]

I'm trying to use the find command to list the size of a certain set of files but am getting no output. The command I use is: find POD -type f -name *.mp3 -or -name *.ogg -ls Which produces no ...
29
votes
5answers
39k views

Passing named arguments to shell scripts

Is there any easy way to pass (receive) named parameters to a shell script? For example, my_script -p_out '/some/path' -arg_1 '5' And inside my_script.sh receive them as: # I believe this ...
2
votes
1answer
540 views

Autojump auto-complete feature does not work

On my configuration, autojump autocomplete feature does not seem to work. To be clear, autojump works properly, only the autocomplete feature fails to work. When I press the <TAB> key, the ...
5
votes
1answer
248 views

Where is $_ defined by POSIX?

In the comments to the accepted answer to this Unix & Linux StackExchange question, it is stated that $_ is "one of only some 7 special parameters defined by POSIX". I can't find that definition ...
5
votes
6answers
21k views

How to split a string into an array in bash

I have a problem with the output of a program. I need to launch a command in bash and take its output (a string) and split it to add new lines in certain places. The string looks like this: ...
1
vote
2answers
105 views

Renaming a whole folder content

I'm on OSX 10.9.2 (BASH 3.5) and I wanted to rename a whole folder content names. So I run a script and somehow ended with this: s01eDavid.Letterman.2014.02.27.Stupid.Human.Tricks.x264-SWOLLED.mp4 ...
13
votes
2answers
41k views

What is the purpose of .bashrc and how does it work?

I found the .bashrc file and I want to know the purpose/function of it. Also how and when is it used?
1
vote
2answers
32k views

In bash, how can I echo the variable name, not the variable value? [closed]

Suppose that I have a variable var in bash. I can assign a value to it. For example, I will make it a string: var="Test" I want to echo the name of var, not the value held by var. (I can do the ...
1
vote
4answers
1k views

What's the difference between $@ and $* [duplicate]

According to this page, $@ and $* do pretty much the same thing: The $@ holds list of all arguments passed to the script. The $* holds list of all arguments passed to the script. After searching ...
3
votes
2answers
932 views

Identify partition by mount point

How can we identify what partition a filesystem is mounted on in Linux when the partition is not directly referenced in df output? For example, our system's fdisk output is: Device Boot ...
1
vote
2answers
201 views

How to properly launch a program and make possible to redirect its running output (stdout and stderr) at a later stage?

The problem is quite simple: I find useful to have the possibility to switch on (and off) the output of some running program in each moment I need. To be more precise I want to be free to redirect ...
1
vote
3answers
300 views

Why doesn't my command work when aliased?

I use ps -ef | grep catalina | grep -v grep to print the tomcat process running on the system: kshitiz 7099 1 0 May11 ? 00:02:29 /usr/lib/jvm/jdk1.8.0/bin/java ...
0
votes
1answer
45 views

Is there a way to make git commit have -v as a default?

I have git () { [ $1 = commit ] && command git commit -v "${@:2}" || command git "$@"; } It makes git commit have -v as a default, otherwise pass on the params and do whatever the git ...
1
vote
2answers
229 views

Why we can not see a single hyphen from $0 on a login shell invoked with `--login` option?

man bash says, A login shell is one whose first character of argument zero is a -, or one started with the --login option. When we invoke a terminal such as mintty - on Cygwin, we can see a ...
2
votes
1answer
764 views

Using Fifo hang script

out="$katalog/out" # wyjscie fifo="$katalog/fifo" # wejscie mkfifo $fifo touch $out [...] #k ./a.out <$fifo >$out & pid=$! [...] # get input line by line loop start echo "$liniain" >> ...
0
votes
1answer
551 views

Creating MySQL database and user without password

I am building a set of bash scripts which basically prepare apache virtual hosts, git repositories and other stuff on a cloud server. So far so good, everything is working, but a big problem occurred: ...
0
votes
1answer
389 views

bash using grep and sed

This is for our weekly prac, no marking or grade (we don't even get the answers!) I'd really appreciate it if anyone has the time to help explain this exercise to me, as I'm trying to get this work ...
1
vote
1answer
2k views

Escaping multiple backticks in a sed call

I need to perform search and replacement iteratively in several SQL statements: From: CREATE TABLE `Old_Name` ( To: ALTER TABLE `Old_Name` RENAME TO `New_Name` The above query contains ...
11
votes
2answers
2k views

How to document my custom bash functions and aliases?

Problem: I have multiple bash functions and aliases. I can't remember all of them off the top of my head, so I usually end up opening my .bash_functions and .bash_aliases files to find what I need. ...
4
votes
3answers
240 views

How to send SIGKILLs to entire pipeline?

while true; do # process substitution instead of usual pipeline to avoid waiting for all programs handle_input_with_timeout < <( prog1 | prog2 | prog3 ) echo "Data stopped flowing. ...
4
votes
2answers
95 views

Generating commands with variable expansion in a loop

I want to create local aliases while I work in certain directories. For example, I would like to have the following in a file named local_alias alias foo='bar' I wanted to write a cleanup script to ...
8
votes
3answers
499 views

How do I capture the exit code / handle errors correctly when using process substitution?

I have a script that parses file names into an array using the following method taken from a Q&A on SO: unset ARGS ARGID="1" while IFS= read -r -d $'\0' FILE; do ARGS[ARGID++]="$FILE" done ...
26
votes
5answers
28k views

Solving “mv: Argument list too long”?

I have a folder with more than a million files that needs sorting, but I cant really do anything because mv outputs this message all the time -bash: /bin/mv: Argument list too long I'm using this ...
3
votes
3answers
12k views

How can I run a “grep | grep” command as a string in a bash function?

I'm trying to build a command that pipes the results of one grep command to another grep command in a bash function. Ultimately, I want the command executed to look like this: grep -I -r FooBar ...
2
votes
1answer
6k views

wget a file, logging the output and showing the output on prompt

In a bash script, I must download a file from the web. I the wget command for doing this. I would like to log the output of the wget command, and at "the same time" have the output prompting on ...
2
votes
3answers
232 views

Make grep work for special filenames

I have a set of txt files whose names may contain space or special characters like #. I have a grep solution grep -L "cannot have" $(grep -l "must have" *.txt) to list all the files who have must ...
0
votes
1answer
367 views

Nagios : How to monitor windows host from linux “by command line”?

I need help to monitor windows host using command line in Nagios. As we can monitor Remote Linux host by NRPE (check_nrpe)using command line as : /usr/local/nagios/check_nrpe -H localhost -c ...
1
vote
2answers
165 views

numfmt invalid suffix input

I am using numfmt to convert a remote file's Content-Length from bytes to IEC format, i.e. 21M $ curl -sI http://jruby.org.s3.amazonaws.com/downloads/1.7.12/jruby-bin-1.7.12.tar.gz|grep Length|cut ...
1
vote
1answer
120 views

How to turn on all default binding keys of vi-editing-mode on bash?

I am using vi-editing-mode on Bash. According to man readline, there are a couple of default binding keys working on vi-editing-mode. Some keys work well, but some other default keys do not work. ...
3
votes
3answers
1k views

How to set the number of commands history recalls

I am using bash. To browse my command history I am calling the history command which I believe is calling the Gnu program of the same name. (I don't know if there's a better bash specific way). In ...
1
vote
2answers
257 views

find command throws errors when inside function

I can run the following command in bash without any errors: $ find /d/Code/Web/Development/Source/ \( -name '*.cs' -o -name '*.cshtml' \) -exec grep -IH UserProfileModel {} \; I wrote a function in ...