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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0answers
34 views

What does && mean in cd “$OLDPWD” && pwd? [duplicate]

What does && mean in cd "$OLDPWD" && pwd? Is it used to connect two commands and run them sequentially in some way? Is it a logical operator of bash?
0
votes
1answer
236 views

shell script edited on windows displays unexpected error message [duplicate]

I am having some trouble running a script to ssh to a remote server. If I simply ssh from the command line I have no trouble reaching the server, but when I run a script to do this I get an error, ...
5
votes
2answers
1k views

How does exec bash builtin work internally?

From this link I get the following about exec bash builtin command: If command is supplied, it replaces the shell without creating a new process. How does it exactly replace the shell (i.e. ...
5
votes
1answer
122 views

How can I create an alias that passes additional arguments?

I have an executable that I use often: /dir1/dir2/dir3/dir4/executable argv[1] argv[2] argv[3] I know that I can set an alias for the executable: alias myexecutable = ...
0
votes
1answer
239 views

How can I update BASH [duplicate]

How can I update BASH? I noticed that there are version 4.2.45 env x='() { :;}; echo vulnerable' bash -c "echo this is a test" this is a test cat /etc/redhat-release CentOS release 5.11 (Final) rpm ...
2
votes
3answers
638 views

Redirect stderr and stdout to another file descriptor

exec 6>&1 will copy file descriptor 1 onto 6. But how can I copy both stderr and stdout (1 and 2)to file descriptor 6 ?
4
votes
3answers
468 views

Better way to run single for loop instead of two for loops

This works but the way I did this is kind of silly. Is there a better way to do this? for e in $(ipcs | awk '{print $2}'); do [[ "$e" = "Semaphore" ]] && break echo $e ipcrm shm ...
8
votes
3answers
6k views

How do I auto complete a command from the command history? [duplicate]

Is there a key combination for bash to auto compete a command from the history? In ipython and matlab for example this is achieved by pressing up arrow after typing a few characters.
5
votes
1answer
3k views

How can I run a bash variable as a command exactly without additional quotation? [duplicate]

I'm trying to make a script which needs to save a command to be run as a string. The string in question needs to contain quotes, and when attempting to execute it bash adds additional quotation ...
-1
votes
1answer
106 views

syntax error: unexpected end of the file

#!/bin/bash #organization: Seneca College #Purpose: Validate a date #Usage: chkdate year month day # year=$1; month=$2; day=$3; extra=$4 if [[ "$year" == "" || "$month" == "" || "$day" == "" ]]; then ...
0
votes
1answer
66 views

how to select multiple exit

I'm new to bash scripting and I don't understand what's wrong with this specific part of my script. im trying to select all the exit that have in my script. and trying to put in conditon that if all ...
4
votes
3answers
695 views

Can you source a “here document”?

Let's say I have a bash script that acts as a config file for another bash script: config.sh: verbose=yes echo "Malicious code!" name=test script.sh: source config.sh echo "After sourcing: ...
1
vote
1answer
213 views

Shellshock - not vulnerable with bash version 4.1?

We have several Amazon servers. It has bash version 4.1.2. Kaspersky claims that all bash versions up to 4.3 are unsafe. When I do this test... env x='() { :;}; echo vulnerable' bash -c 'echo hello' ...
2
votes
2answers
3k views

Bash not equal string comparison

Why does this cause an infinite loop? #!/bin/bash while [[ "$(ipcs | awk '{print $2}')" != "Semaphore" ]]; do #Gonna get rid of the echo after working echo "$(ipcs | awk '{print $2}')" #I wanna ...
2
votes
0answers
68 views

Why do some processes pass on their cpu usage to another process when it ends?

I have wondered this for a while. For example, lets say process1 is a process that uses a lot of cpu power, like 90%. Its a video game. Then i have process2 which uses 10-12% cpu. Its a web browser. ...
1
vote
1answer
829 views

Why is variable assignment preceding command ignored? [duplicate]

The bash 4.1 manpage states (emphasis added)... Simple Commands A simple command is a sequence of optional variable assignments followed by blank-separated words and redirections, and ...
2
votes
1answer
17k views

Bash if statement [: missing `]' error [duplicate]

I am having trouble with bash. I am trying to put a command in an if statement and then compare it to a string. This works perfectly. echo $(ipcs | grep Shared | awk '{print $2}') When I put it in ...
2
votes
1answer
385 views

Copy multiple files and create the target directories at the same time?

I read How can I copy a file and create the target directories at the same time? But the solution there only works if you want to copy one file. How would I copy multiple files into a directory, ...
1
vote
3answers
1k views

bash script that reads user input and uses “cal” command to validate dates

I want to write a script that reads my input (for example if my script is called "check", then I would type "check 9 4 1993" and that input would go through the cal command and will check through the ...
2
votes
0answers
42 views

bash syntax error near unexpected token `(' - but everything looks like it should work [duplicate]

I'm trying to write a bash script which will copy a bunch of files and directories from a directory, omitting a couple but taking everything else. I have got a command that does this and works from ...
6
votes
2answers
888 views

How do I delete all of a set of files in a random order?

I have a set of files, all that are named with the convention file_[number]_[abcd].bin (where [number] is a number in the range 0-size of drive in MB). i.e there is file_0_a.bin, file_0_b.bin, ...
0
votes
1answer
490 views

Shell script permission denied despite +x flag

This is an odd one, it only happens on one server (shared hosting, so I have limited access to configuration and logs), but I can't wrap my head around it. I have a shell script which runs some app's ...
4
votes
2answers
7k views

How to check whether a process is daemon or not?

I have written a small daemon that starts at the boot time and does all the things perfectly like writing in the log file. But I want to know, how can we check whether that process is daemon or not? ...
1
vote
2answers
162 views

bash question about if and then [duplicate]

I'm writing this in my script. It has other parts but I'm getting stuck on this part only. if [[$# == $year $month $day ]] ; then cal $day $month $year fi When I run this it give me this msg: ...
0
votes
1answer
94 views

how to write this if command?

my script name is 1. when i type in "1 2012 12 12". it shows current date calendar and when i enter a invaild date like "1 2323232" cal gives me a error so how could i put that in if loop that if it ...
5
votes
2answers
513 views

Did the shellshock bash fix break basic command line tools like echo and cat? [duplicate]

I used to be able to do things like: X=123 cat <<EOF X is $X EOF or even simpler: X=123 echo $X The first one still seems to work on Mac OS X after install the bash fix, however neither ...
-1
votes
1answer
544 views

how to create a dynamic password thats between 8 and 16 characters [duplicate]

This is my password generator and it generates 8 characters and shuffles them. But i need to make it dynamic length. How would i go about doing that. So the output would be different length between 8 ...
0
votes
1answer
602 views

use EOF in a one-liner?

I have a simple script that executes commands on remote host using ssh and EOF I was trying to do it with a one-liner at command line but I couldn't figure out how to do the EOF outside of a script. ...
1
vote
0answers
111 views

export -f in .bashrc after upgrade to bash 4.3.30 kills builtins?

I recently upgraded my bash (Mac OS X 10.6.8) from 3.2.48(1) to 4.3.30(1) via macports, and while the install seems to have gone smoothly, the two spots in my ~/.bashrc where I had export -f myfunc; ...
0
votes
1answer
340 views

Can call login command from terminal

I want to create a user using useradd from root in my terminal window, after it I call passwd to set user's password. So I cant call login username because when I call it from terminal it closes ...
0
votes
1answer
280 views

generate password that is random length between 8 - 16 ( i have the generator but its not dynamic) [duplicate]

This is my password generator and it generates 8 characters and shuffles them. But i need to make it dynamic length. How would i go about doing that. So the output would be different length between 8 ...
2
votes
4answers
3k views

Creating symbolic link recursively

I essentially want to run this command... ln -s /opt/gitlab/embedded/service/gitlab-shell/hooks/ /var/opt/gitlab/git-data/repositories/web/*/hooks This would create a symbolic link in all folders ...
2
votes
3answers
1k views

How to nest quotes in bash commands

I want to test the result of this command: dmesg | grep "Firmware patch 1563" Therefore, I try to write something like this: if [ "`dmesg | grep "Firmware patch 1563`" == "" ] But it doesn't ...
2
votes
1answer
134 views

Replace pattern in file with pattern in second file

I want to replace part of a file's data, with data from another file. Suppose file1 has data as is written below and file2 has some data I want to store and replace file1 data from file2 from ...
4
votes
2answers
199 views

Where do bash completion functions come from?

I have a Raspberry Pi running Raspbian (Debian Wheezy). I entered set in a terminal and was surprised by the long list. This seems to be almost entirely git functions — ~3700 lines of them. ...
1
vote
1answer
273 views

Custom tab-completion in bash's `read`

Is there a way to "import" a list of words into bash's read builtin to have custom tab-completion? I've been writing a wrapper script for suckless' minimalist irc client "ii", and I don't have a way ...
0
votes
2answers
443 views

Get the file list in an HTML directory listing

I can get all files on the bash patches site by downloading them in a sequence: SEQ=$(seq -f "%03g" 1 30) for i in $SEQ; do wget http://ftp.gnu.org/gnu/bash/bash-4.3-patches/bash43-$i; done But ...
4
votes
3answers
4k views

How to escape single quotes correctly creating an alias [duplicate]

I've been given this one-liner to know how much memory my processes consume. $ ps -u $USER -o pid,rss,command | \ awk '{print $0}{sum+=$2} END {print "Total", sum/1024, "MB"}' Now I'd like to ...
2
votes
1answer
454 views

How to remove file log with file name

Assume, I have log files with this name format. NameLog.log.2014-09-27 NameLog.log.2014-09-28 NameLog.log.2014-09-29 NameLog.log.2014-09-30 NameLog.log.2014-10-01 NameLog.log.2014-10-02 ...
37
votes
3answers
7k views

What are the shell's control and redirection operators?

I often see tutorials online that connect various commands with different symbols. For example: command1 | command2 command1 & command2 command1 || command2 command1 && command2 ...
3
votes
2answers
271 views

How do I echo a lot of content in a bash script?

I would like to do echo "[this thing]" This thing is \documentclass{article} \usepackage{rotating} \usepackage{pdfpages} \usepackage{verbatim} \usepackage{amsmath, amsfonts, amssymb, textcomp, ...
5
votes
2answers
967 views

sed + how to delete the second character “.” from the line

how to delete the second character "." from the line what I have is this ( but its remove the first "." from output uname -r | sed s'/\./ /' 2 6.18-164.2.1.el5PAE while I need the following ...
1
vote
1answer
133 views

cd to a child directory of a symlink fails

To build a kernel module, you have to do make -C where -C is cd functionality. As my make failed a lot of times, I found this: [root@ror6ax2 modules]# ls -l /lib/modules/`uname -r` | grep build ...
0
votes
1answer
128 views

rpm + where RPM installed the files/scripts PATH

I installed the following RPM file rpm -Uvh --repackage /var/tmp/bash-3.2-33.el5_11.4.i386.rpm warning: /var/tmp/bash-3.2-33.el5_11.4.i386.rpm: Header V3 DSA signature: NOKEY, key ID 37017186 ...
0
votes
4answers
86 views

Bash multiple rename in one line: is possible?

Is possible to rename and substitute on fly with bash? for example i have VTS_01_1.VOB VTS_01_2.VOB VTS_01_3.VOB I want to rename for use in mencoder with movie_1.avi movie_2.avi,etc.. I ...
2
votes
2answers
61 views

Is there an improved version of “pick” that will work with filenames with spaces?

Is there a version of the pick script that will work properly with spaces in the filenames? This is a tricky question—pick is trivial to enhance to work with spaces in filenames, but the output ...
1
vote
1answer
2k views

Trying to multiply a float in bash not working [duplicate]

I have this script that is to rescale images to a percentage value #!/bin/bash percent=$1 echo $percent for img in `find *.png`; do echo Processing file $img width=$( mdls $img | grep ...
1
vote
1answer
98 views

Ran php file contents in bash, could some commands be executed?

I accidently pasted this in bash as super user on production server. Now I'm eating nails. I looked through each line and most of them produce syntax error. But is there something evil that could ...
1
vote
4answers
937 views

How to run a script in multiple instances ? ( Ubuntu server )

How can I run a script in multiple instances in Ubuntu server? For example, I have a long running script named scanner.sh placed in /usr/bin/, which I wish to run the script in 10 parallel ...
1
vote
2answers
930 views

A tiny and simple script fail and this is the output “No such file or directory”

The script is: #!/bin/bash IFS=" " command="ls /tmp" for file in `$command`; do echo $file done And the output is: $ ./test.sh ./test.sh: line 17: ls /tmp: No such file or directory