Questions about bash only, as opposed to other Bourne/POSIX shells. For all Bourne/POSIX-style shells, use the /shell tag instead.

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2
votes
2answers
353 views

Why does “$i | sed” not work?

I have this code: if [ $i | sed -e "s/^.*\(.\)$/\1/" = "/" ] then echo "folder" else echo "file" fi where $i is something like this app4/ The code above should get the last char of the ...
2
votes
1answer
399 views

Get pid of long running command executed via at

I would like to spawn a persistent netcat server. My command of choice is the following: echo "bash -c \"while [ 1 ]; do nc -l -p 1111 >> check; done\"" | at now I am wondering how I can get ...
-2
votes
1answer
286 views

Why does this script show all files in the directory and not just PDF files?

I wrote the script below to find the number of PDF files in a given directory. However, it instead shows all the files in the directory: #!bin/bash message="." message1="*.pdf" ls -al $message ...
3
votes
3answers
938 views

Is it a script or is it a binary?

At the end, it looks like it's just a regular sh script: [USER@MACHINE ~/Desktop/D] head -2 truecrypt-7.1-setup-x86 #!/bin/sh CHECKSUM=163123652 but @the scripts end: [USER@MACHINE ~/Desktop/D] ...
2
votes
2answers
2k views

Is the `\` character escaping or becoming part of my ssh key password

If I do: ssh-keygen -N password123\$ -f bobskeys Is \ escaping the $ character or becoming part of the password? Or rather, will bash be doing any escaping before ssh-keygen gets the password ...
5
votes
2answers
3k views

Is it possible to get the error message from previous command which failed when the conditional command runs using ||

I have a helper function: function error_exit { /opt/aws/bin/cfn-signal ... exit 1 } This helper function is used to signal an error. Here is an example of usage: /opt/aws/bin/cfn-init -s ...
3
votes
1answer
653 views

wait for autossh connection to complete

I'm trying to create a script that runs a few commands that take a long time to execute and require a constant connection, but autossh user@server wait $! #or wait ${!} commandA commandB doesn't ...
0
votes
1answer
683 views

-bash: command: command not found [closed]

I'm trying to run a program from the command line, and I got a -bash: command: command not found error. What can I do to troubleshoot/fix the problem?
13
votes
4answers
18k views

Script to change current directory (cd, pwd)

I want to run a script to simply change the current working directory: #!/bin/bash cd web/www/project But, after I run it, the current pwd remains unchanged! How can I do that?
2
votes
0answers
110 views

How do I get this Bash-script to work? [duplicate]

Possible Duplicate: How to name a file in the deepest level of a directory tree How do I get this script to work? The goal is to find the directory at the deepest level in the directory ...
2
votes
2answers
1k views

su - username -c “./script.sh” -> no such file or directory

We have: a user nico. a folder /home/nico/script_home with some bash scripts: main.sh subscripta.sh sqlscripta.sh We connect as root and cd /home/nico/script_home/ Finally we run ./main.sh We ...
16
votes
5answers
23k views

#!/bin/bash - no such file or directory

I've created a bash script but when I try to execute it, I get #!/bin/bash no such file or directory I need to run the command: bash script.sh for it to work. How can I fix this?
6
votes
1answer
561 views

“Safe mode” on Linux?

Under RouterOS/Cisco there is a function called "safe mode". When someone presses CTRL+X then the terminal goes in "safe-mode" that meant that if the terminal exists in a "bad way", ex.: the user ...
2
votes
1answer
3k views

Script to SCP files works manually but not through cron

I'm using CentOS 5.6. The below code might have some typos as I needed to change real info to fake info for security reasons: backup.sh #!/bin/bash set -vx rm -v /server/temp_db.gz rm -v ...
3
votes
6answers
2k views

How to name a file in the deepest level of a directory tree

How do I name one random file in the deepest level of a directory tree using basic Bash commands and script? I was searching for a way to do it as an one-liner and without functions. Assuming also ...
8
votes
5answers
4k views

Displaying seconds as days/hours/mins/seconds?

Is it possible to easily format seconds as a human-readable time in bash? I don't want to format it as a date, but as the number of days/hours/minutes, etc...
3
votes
5answers
355 views

evaluate multiple patterns from program output and write into pattern specific files

I have a script outputting some value/numbers and I want to split those into two files. I am looking at something like: ./runme.sh | grep 'ook' >> ook.out | grep 'eek' >> eek.out Where ...
3
votes
1answer
74 views

Calling a script on each line of a file

I have a bash script that takes 3 arguments: $ do_something foo bar baz and a file with several lines, each with different 3 args. I want to execute the script as a cronjob, and each time it's ...
2
votes
2answers
2k views

How to fix this error? make: *** [obj/local/armeabi/libgstaudioflinger.so] Error 1

I am trying to install this following framework from my Linux Fedora box to Android using there SDK/NDK. But after following all instruction its getting still failed to get build. Any idea how to fix ...
1
vote
1answer
848 views

grep searchstring /etc/crontab strange behavior in BASH script

I am working on a BASH script which creates automated backups via the crontab. I am trying to use myVARIABLE=`grep backup /etc/crontab` to return lines containing "backup" if an entry has already ...
0
votes
1answer
824 views

POSIX and Bash, sh shorthand, for compound if statement

I prefer to do my sh commands in shorthand, And I prefer to be in POSIX. Truthfully, if the script can run on Dash, that is good enough. Which means using the test command [, not the extended [[. I ...
10
votes
4answers
2k views

Abbreviated current directory in shell prompt?

vim has a really nice feature which it utilizes in its paths when they're a bit long: It abbreviates the path to the document in the tab at the top. Is there a way to do something similar to this ...
2
votes
1answer
764 views

Redirecting output when I execute “bash -c …” from a C program

Say I have a C program and in it I want to execute a shell command and redirect its output to file, by using the stdlib system function. system("bash -c \"echo $HOME\" > a.txt"); Now this is for ...
14
votes
11answers
2k views

“Bookmarks” for bash

Navigating several layers of nested directories is often a pain. On Firefox, it is easy because they have bookmarks. So what I'd like to do to bookmarks a file is to type: $ go --add classes ...
10
votes
1answer
2k views

Readable comments on separate lines in a multi-line bash command with pipelines?

When creating shell scripts using pipelines, and using the backslash to continue lines, I want to insert comments on separate lines, in a robust, readable and portable fashion. For example, given ...
2
votes
1answer
4k views

How to set a new password from bash?

I'm using busybox with a limited passwd (I don't have --stdin option) and without chpasswd and I need to change the password of an user from bash. Here is my best result: echo newpassword > ...
1
vote
2answers
1k views

autocomplete filenames using compgen

As part of a larger autocomplete function I'm writing, I want to use compgen to generate a list of files. I read the bash manual entries for compgen and complete, and from there I assumed that the ...
16
votes
2answers
29k views

Refresh env variables after editing bashrc file

I frequently edited the .bashrc file to export new environment variables. Rather than close the console and start a new one to refresh the env variables, is there a convenient way to refresh?
13
votes
1answer
9k views

How do I set a user's default .bashrc file?

On Ubuntu 10.4 I have edited the /etc/bash.bashrc file to set some variables like the command history size (HISTSIZE=5000), however if I create a new users Ubuntu by default gives them a .bashrc file ...
14
votes
4answers
25k views

How to read from two input files using while loop

I wanted to know if there is any way of reading from two input files in a nested while loop one line at a time. For example, lets say I have two files FileA and FileB. FileA: [jaypal:~/Temp] cat ...
23
votes
4answers
20k views

How to delete line with echo?

I know that I could delete the last three chars with: echo -ne '\b\b\b' But how can I delete a full line? I mean I dont want to use: echo -ne ...
10
votes
3answers
5k views

How to /dev/null background processes “informational” output?

[USER@SERVER ~] sleep 3 & [1] 5232 [USER@SERVER ~] [1]+ Done sleep 3 [USER@SERVER ~] How do I /dev/null these two messages?: [1] 5232 [1]+ Done sleep ...
7
votes
2answers
356 views

Send task to background in an “if”

Why is this? if true; then sleep 3 &; fi bash: syntax error near unexpected token `;' I want to run sleep 3 in the background so that the command ["sleep 3" is just an example] would run ...
4
votes
2answers
581 views

How can I copy all users .bash_history files into my home directory?

I am running as root. I want to copy all the users on the system's .bash_history files into my home directory. I can do this to combine all of them into one, but then I can't tell who's commands are ...
2
votes
1answer
3k views

Why my $PATH is not inherited by the invoked bash?

I work on an AIX system where I have no administrator privileges. It has several shells installed, default being tcsh. I am not allowed to change the login shell. Usually I start my session from exec ...
6
votes
4answers
2k views

Colored FIND output?

Is it possible to get colored output from the find command? That is, in the path of each found item, directories are blue, executable scripts are green, et cetera? I'm using version 4.4.2 of GNU ...
14
votes
2answers
10k views

How are parenthesis interpreted at the command line?

While reading up on how to set up grub, one article mentioned that I need to use a syntax like echo \(hd0,0\) >> /boot/grub/grub.conf or echo '(hd0,0)' >> /boot/grub/grub.conf ...
236
votes
6answers
397k views

How to correctly add a path to PATH?

I'm wondering where a new path has to be added to PATH environment variable. I know this is accomplished editing .bash_rc (for example), but it's not clear how to do this. This way: export ...
1
vote
1answer
1k views

How to put a command's result into a variable? [duplicate]

Possible Duplicate: Storing output of command in shell variable Can anyone advise please how can I put the result of jps | awk '$2~/Bootstrap/{print $1}' into a variable so that I can use ...
9
votes
2answers
4k views

Parallelizing a for loop

I want to parallelize the for loops of the following code. How to do this? #!/bin/bash N=$1 n=$2 for (( i=1; i<=$N; i++ )); do min=100000000000000 //set min to some garbage value for (( ...
21
votes
2answers
32k views

How to check if there are no parameters provided to a command?

How do you check if $* is empty? In other words, how to check if there were no arguments provided to a command?
10
votes
1answer
482 views

How to output string completions to stdout?

Some of the git commands have many options, and it would often be useful to search through them for the one I need - I was just looking for the option which controls the TAB width in git-gui, but ...
44
votes
2answers
24k views

Awesome symbols and characters in a bash prompt

I just ran across a screenshot of someone's terminal: Is there a list of all of the characters which can be used in a Bash prompt, or can someone get me the character for the star and the right ...
7
votes
1answer
839 views

Screen cuts off beginning of long command when accessed through bash history

I'm using the default versions of bash and screen in OS X Lion. When I'm in a screen session and I scroll back through the bash history and I come to a command that is long enough to wrap. I might ...
6
votes
2answers
307 views

Output of which command used for input to cd

I would like to take the output of a which command, and cd to the parent directory. For example, say I have the following: which someprogram With output: /home/me/somedirectory/someprogram And I ...
0
votes
1answer
766 views

source .bashrc command doesn't work

I installed TinyOS on RedHat for academic purposes. Now I can't log in to the system. I logged in in single user mode. Then I tried to log in. I couldn't login as any user. I couldn't start the X ...
0
votes
1answer
9k views

Different ways of using expr command [closed]

I'm trying to learn the bash expr command inside and out. What are some of the most basic to the most creative/tricky/unexpected ways to use the expr command? Small, manageable examples are great.
10
votes
4answers
19k views

Grep: how to add an “OR” condition?

I am a total regex newbie. I find it confusing and I avoid it like the plague (wanna take some guesses as to why I'm not good at it?). But I suspect it might be the solution to my question. Which ...
3
votes
3answers
1k views

Implementing rollback in bash

I have a script that is composed of staged operations which work mostly in a start/stop/status manner. The issue I have is that when starting, each of the operations can fail and I need to do a safe ...
6
votes
2answers
2k views

Pasting from clipboard to vi-enabled zsh or bash shell

I'd like to be able to paste from the system clipboard (or text selection) into my "vi-like" shell prompt using the keyboard. I normally use zsh and sometimes bash. In both cases, I have the shell set ...