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

learn more… | top users | synonyms

2
votes
1answer
1k views

Convert pdf to jpg keeping the same name; resize & create thumbs then rename?

I have a lot of pdf files (3308) on which I must apply four steps: 1) I have to convert all to jpg I found this little script on the web with ImageMagick: batch converting pdf to jpg I want to do ...
3
votes
2answers
1k views

Bash prompt keeps disappearing

I have a weird issue where my Bash prompt often completely disappears on a backspace. Doesn't make any sense to me, but it happens often: I can't really think of why this is happening. Am I ...
1
vote
3answers
429 views

Evalute passed in variable in bash

Is there a way to pass in a variable as an argument to a bash script and have it evaluated scoped by the bash script? Given: # cat /path/to/file/of/host/names bob tom joe etc... # dofor FILE=$1 ...
2
votes
2answers
473 views

How to execute script on logging out?

I'm reading The Unix Programming Environment. There is an exercise question to print how much CPU time you have consumed when you log off by editing .profile. I tried with this trap 'times' 0 1 2 15 ...
1
vote
1answer
465 views

Finding duplicate files

I need to write a bash script that finds duplicate files, but in addition to md5sum it needs to use cmp to do the final check. I tried the command below in my shell. How can I add a loop and put it ...
2
votes
1answer
6k views

send html using mailx

I'd like to send a html file from a host using mailx but instead of interpreting it as html it would send it out as text (html codes). Is there a way to send it as html? (cat <<EOCAT Subject: ...
6
votes
2answers
3k views

Distinguishing a regular file from a symlink

I'm writing a bash script that needs to distinguish a regular file from a symlink. I thought I could do this with if/test expression, but it doesn't work as I expected to: $ touch regular_file $ test ...
1
vote
2answers
1k views

How to group grep results?

I have a file that contains results grouped into categories. For example: checking results for $var here are some results1 for $var status ok here are some results2 for $var status ok here are some ...
8
votes
9answers
5k views

linux diff tools: create list of modified files

How do I create a list of modified files programmatically using linux command line tools? I'm not interested in the difference in any particular file (delta, patch). I just want to have a list of new ...
5
votes
4answers
1k views

Last failed command in bash

The $? variable holds the exit status of last run command. Is there a variable that holds last run command itself?
6
votes
4answers
398 views

Bash: test whether original script was run with `-x`

Is it possible to test whether a bash script was executed with -x? I'm writing a script which also runs some remote scripts, and I'd like to be able to do something like: USE_X="$( run_with_x ...
3
votes
2answers
2k views

Ignore escape characters when printing string in shell script

I just wrote a simple shell script to save a LaTeX expression as a PNG file. It works fine, except for the LaTeX-syntax for "next row", i.e. the double backslash \\. When for instance my input ...
2
votes
2answers
296 views

perl regex replacing globally when global not selected

I'm using Ubuntu 11.04 and wrote a small script that searches within text files for certain "tokens" and replaces with some a prewritten snippet from a template file of the same name. The text files ...
13
votes
3answers
2k views

How to delete part of a path in an interactive shell?

Is there a shortcut in bash and zsh to delete one component of a path? For example, if I type ls ~/local/color/, and the cursor is at the end of line, is there a shortcut to delete the color/ at the ...
1
vote
1answer
341 views

root shell isn't using --color=auto

Does anyone know why the root user doesn't have a colour coded shell? It would seem to me the one person who navigates the file system the most is the root user, s/he would benefit most from the ...
1
vote
1answer
490 views

Why does curl fail while using this export?

I'm doing some stuff with Facebooks FQL at the moment, and I'm using curl on the command line to test some of the responses of it. I'm also using export to keep the params seperated for easy editing. ...
9
votes
2answers
2k views

Piping for loop output prevents local variable modification

I'm trying to write a simple bash function that takes, as its arguments, a number of files and/or directories. It should: Fully qualify the filenames. Sort them. Remove duplicates. Print all that ...
6
votes
1answer
5k views

Running a bash script from a zsh shell

I'm having problems running a bash script on zsh. The script is similar to the one below and is supposed to run under bash: #!/bin/bash echo "<235234>" | egrep -oe [0-9]+ However, my shell ...
0
votes
1answer
150 views

how will I make interactive login

I'm having trouble in making script with interactive login. I have made one but it doesn't ask the login, it automatically log in when i run the script. i just need the output like this: please ...
4
votes
2answers
263 views

Understanding quotes in a bash conditional instruction

My friend is messing around with Bash scripts and he wanted me to take a look at them (he had another friend do it for him). One of the commands is if [ "`pidof transmmission-gtk`"=0 ]; what ...
2
votes
2answers
826 views

How do I install multiple java command-line programs?

I have a bunch of java command-line programs I've written and would like to install for all users. Building with NetBeans, I get a /dist directory which contains myprog1.jar and a /libs directory ...
9
votes
1answer
686 views

How do you omit “./” when running scripts on current directory

On some tutorials over the internet they can run a script on the current directory without doing: ./script How do you omit this? I am using CentOS 5.6 x64. I want to run it this way script
3
votes
2answers
3k views

From shell, killing a process if wallclock runtime exceeds some predetermined value

I want to start a process from a shell script, allow it to interact with the user (so I cannot just background it, grab the PID, launch sleep followed by sanity checks and kill), but if it is still ...
4
votes
2answers
381 views

Saving tab completion possibilities to a file

Instead of displaying all possibilities on terminal screen, as in: $ ls /etc/<TAB> Display all 230 possibilities? (y or n) I want to save all possibilities to a file. ls /etc/ > file.txt ...
1
vote
1answer
457 views

Changing file extensions [duplicate]

Possible Duplicate: Renaming multiple files (changing extension) Suppose I have a bunch of files with the extension .x and I want to change them so that they have the extension .y. I know $ ...
5
votes
3answers
4k views

Print shell arguments in reverse order

I am a bit stuck. My task is to print the arguments to my script in reverse order except the third and fourth. What I have is this code: #!/bin/bash i=$# for arg in "$@" do case $i in ...
0
votes
1answer
293 views

Non printing characters

I would love to get the mappings to work for keyboard shortcuts shown here http://ascii-table.com/ansi-escape-sequences.php I have the hang of color but for some reason nothing else seems to work!
7
votes
2answers
4k views

Can I automate tar's multi-volume-feature?

Ok, so I've just had a read through this page after a way to improve my current backup solution on my Debian server. Tar seems to be offering a quite nice multi-volume feature, although when I try it ...
20
votes
1answer
3k views

Execute bash scripts on entering a directory

What is the best way to execute a script when entering into a directory? When I move into a new directory I would like bash to execute the projectSettings.bash script much like RVM does.
2
votes
2answers
2k views

How do I cause a watchdog reset of my embedded Linux device

Is there a command like vi > out vi | out That I could use to cause a watchdog reset of my embedded linux device?
8
votes
1answer
3k views

Alias a command to run in the background

I'd like a keyboard shortcut to work as so: > e foo.txt to expand as > emacs foo.txt & It's simple to use alias e=emacs, but how do I insert the & after the filename? I realize it ...
3
votes
2answers
339 views

How can I “cache” a variable in Bash?

I have a bash script which is run every 10m by cron. The script performs an expensive calculation for some value (say variable x=value). I need to "cache" this value for 2-3 hours. What are possible ...
3
votes
3answers
3k views

How to pass a string parameter on bash function?

I have this code that does work: get_parameter () { echo "$query" | sed -n 's/^.*name=\([^&]*\).*$/\1/p' | sed "s/%20/ /g" } But I want to replace the "name" with the parameter that I pass ...
1
vote
1answer
163 views

How does this bash function work?

I'm looking at this short example, and I don't see how this function works: function EXT_COLOR () { echo -ne "\[\033[38;5;$1m\]"; } AFAIK -ne stands for not equal. What are we comparing here? I ...
5
votes
2answers
1k views

Why doesn't “rm *” work when there are files that begin with a hyphen?

from: http://seclists.org/fulldisclosure/2011/Sep/190 [USER@MACHINE ~] mkdir ejha [USER@MACHINE ~] cd ejha/ [USER@MACHINE ~/ejha] touch ize [USER@MACHINE ~/ejha] touch -- -f -i [USER@MACHINE ...
5
votes
3answers
896 views

How can I reset all the bind keys in my Bash?

I bound some keys by mistake, and they don't work any more, such as HOME, END, UP, DOWN, LEFT, RIGHT. Is there a way to reset all the bound keys to their original state?
5
votes
3answers
1k views

How should I add users non-interactively?

I have a set of users I need to add to a new system as part of a BASH script that preps my server. How can I non-interactively add the user, create their home directory, set the group, and enter a ...
3
votes
5answers
879 views

How can I test whether connection to the given host/port is established in Bash?

Currently I'm using netstat for this: if netstat -an | grep ESTABLISHED | grep $address:$port > /dev/null; then # command fi Is there a more elegant solution?
7
votes
2answers
959 views

sharing or synchronizing history between Zsh and Bash

I often find myself switching between Bash and Zsh, and using the history search functionality to recover a command. However, since Bash and Zsh have different history files, I often find that the ...
3
votes
1answer
2k views

Showing GNU screen session name and window title in shell prompt

Is there a way to present the GNU Screen session name and window title in the prompt of the shell (let us say, the Bash prompt defined by PS1)?
2
votes
2answers
467 views

Script to prepend the files path to a file recursively

I work as a grader and files submitted to me end up in a folder named with the student's name which is itself inside a specific folder on my linux share. Currently I go through each source file and ...
9
votes
5answers
14k views

Is there a way to set the size of the history list in bash to more than 5000 lines?

No matter how much I set the HISTSIZE environment variable to be larger than 5000, when printing the history list with the history builtin, it prints only the last 5000 commands. I need that because I ...
6
votes
1answer
1k views

Customizing bash shell: Bold/color the command

There are a number of tutorials/posts online (e.g. http://www.cyberciti.biz/faq/bash-shell-change-the-color-of-my-shell-prompt-under-linux-or-unix/) about how to customize your prompt in bash by ...
2
votes
1answer
149 views

Need to find a cronjob

I have a problem, some user ,and I'm not sure who, on one of my servers wrote a cronjob that executes every night at midnight. The cronjob creates a sql dump of a database which is then grabbed by ...
66
votes
13answers
94k views

How can I resolve a hostname to an IP address in a Bash script?

What's the most concise way to resolve a hostname to an IP address in a Bash script? I'm using Arch Linux.
4
votes
4answers
1k views

Which stream does Bash write its prompt to?

I am trying to redirect all output from bash (prompt, user input, results) to a file Example: /bin/bash > file.txt 2>&1 I thought that would work, but I'm not getting the prompt. Can ...
4
votes
1answer
677 views

How to stop Bash appending history

I am having a lot of trouble setting up the terminal history of Bash the way I want. I would like to have no duplicate entries and if I enter a command I want it saved and the duplicates above ...
2
votes
1answer
1k views

Load my .profile for bash in Emacs terminal buffer? (multi-term mode)

I've got multi-term mode (derived from ansi-term) with bash started in Emacs 23.3, which is a terminal emulator running in Emacs. However, I noticed that it did not load my user profile, including ...
3
votes
2answers
304 views

Using `select` command to print menu in Linux

OS - Linux 64-bit I am trying to implement a simple menu using select command. The script (for testing purposes) is as follows #!/bin/bash echo "*******************" PS3='Select an option and press ...
7
votes
1answer
457 views

Note-taking and outlining using Vi: On startup, highlight tags and display tags in a preview window [duplicate]

I am using vi as a note-taking and outlining tool and therefore I thought that this stackexchange site would be appropriate to ask this question. I am constructing the "tags" file by myself. What I ...