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137
votes
10answers
12k views

In Bash, when to alias, when to script, and when to write a function?

It's taken me almost 10 years of Linux usage to ask this question. It was all trial and error and random late-night internet surfing. But people shouldn't need 10 years for this. If I were just ...
19
votes
4answers
919 views

difference between function foo() {} and foo() {}

I can define bash functions using or omitting the function keyword. Is there any difference? #!/bin/bash function foo() { echo "foo" } bar() { echo "bar" } foo bar Both calls to functions ...
18
votes
1answer
1k views

Aliases vs functions vs scripts

This site says, "Shell functions are faster [than aliases]. Aliases are looked up after functions and thus resolving is slower. While aliases are easier to understand, shell functions are preferred ...
12
votes
4answers
4k views

Can I “export” functions in bash?

source some_file some_file: doit () { echo doit $1 } export TEST=true If I source some_file the function "doit" and the variable TEST are available on the command line. But running this script: ...
12
votes
5answers
343 views

Stateful bash function

I’d like to implement a function in Bash which increases (and returns) a count with every call. Unfortunately this seems non-trivial since I’m invoking the function inside a subshell and it ...
9
votes
4answers
2k views

Executing user defined function in a find -exec call

I'm on Solaris 10 and I have tested the following with ksh (88), bash (3.00) and zsh (4.2.1). The following code doesn't yield any result: function foo { echo "Hello World" } find somedir -exec ...
8
votes
3answers
327 views

Running an executable in PATH with the same name as an existing function

Sometimes I define a function that shadows an executable and tweaks its arguments or output. So the function has the same name as the executable, and I need a way how to run the executable from the ...
8
votes
1answer
1k views

How to get current buffer's filename in emacs?

One of the main features I miss about Vim, is that it always saves the filename of the current file in the % buffer (more info). That allows launching commands easily like: ;; compile current file :! ...
7
votes
7answers
3k views

Doing simple math on the command line using bash functions: $1 divided by $2 (using bc perhaps)

Sometimes I need to divide one number by another. It would be great if I could just define a bash function for this. So far, I am forced to use expressions like echo 'scale=25;65320/670' | bc but ...
7
votes
2answers
621 views

How do I redefine a bash function in terms of old definition?

Is there any way I can redefine a bash function in terms of its old definition? For example I would like to add the following block of code to the preamble of the function command_not_found_handle (), ...
6
votes
3answers
175 views

Display the function body in Bash

I have setup several functions in my .bashrc file. I would like to just display the actual code of the function and not execute it, to quickly refer to something. Is there any way, we could see the ...
5
votes
3answers
221 views

Can you pipe to a .bash_profile function?

I received a great function for highlighting files in Apple's finder using the command-line. It's basically a wrapper for osascript. I got it from Mac OS X: How to change the color label of files ...
5
votes
2answers
367 views

How can I create a function in zsh that calls an existing command with the same name?

How can I write a function in zsh that invokes an existing command with the same name as the function itself? For example, I've tried this to illustrate my question: function ls { ls -l $1 $2 $3 ...
5
votes
3answers
736 views

How to set an alias on a per-directory basis?

Suppose you have an alias go, but want it to do different things in different directories? In one directory it should run cmd1, but in another directory it should run cmd2 By the way, I have an ...
5
votes
2answers
149 views

How to define a Bash function that can be used by different scripts

I have defined a bash function in my ~/.bashrc file. This allows me to use it in shell terminals. However, it does not seem to exist when I call it from within a script. How can I define a bash ...
5
votes
2answers
241 views

Gawk: Passing arrays to functions

Stuck with GNU awk 3.1.6 and think I've worked around its array bugs but still have what looks like a scope problem in a 600-line awk program. Need to verify understanding of array scope in awk to ...
5
votes
1answer
464 views

what is the zsh equivalent of bash's export -f

So I started using zsh. I like it all right. It seems very cool and slick, and the fact that the current working directory and actual command line are on different lines is nice, but at the same time, ...
4
votes
4answers
1k views

How can I pass a command line argument into a shell script?

I know that shell scripts just run commands as if they were executed in at the command prompt. I'd like to be able to run shell scripts as if they were functions... That is, taking an input value or ...
4
votes
4answers
613 views

How to make functions created in a bash script persist like those in .bashrc?

My .bashrc was getting a little long, so I decided to break it up into smaller files according to topic and then call these files from within .bashrc as so #my long .bashrc file bash .topic1rc bash ...
4
votes
2answers
245 views

Combine two commands in .bash_profile

In my .bash_profile file, I'd like to setup a single command alias that is two commands that execute one after another. The first command takes an argument from the command line and the second is ...
4
votes
2answers
311 views

How to test if command is alias, function or binary?

I have command foo, how can I know if it's binary, a function or alias?
4
votes
2answers
188 views

Passing a code block as an anon. function

Is it possible to treat a block of commands as an anonymous function? function wrap_this { run_something # Decide to run block or maybe not. run_something else } wrap_this { do_something ...
4
votes
1answer
179 views

View shell function's current definition

So I am editing bashrc constantly, and I have a terminal open with a working function definition, although bashrc has been updated with a wrong function definition. (Because the definition do not ...
4
votes
2answers
612 views

Bash function not working in Zsh

I have been slowly migrating from Bash to Zsh and have got to the point where everything I have moved across is working well, with one exception. I have a couple of functions in my .bashrc that I use ...
4
votes
4answers
752 views

Is it possible to source a file in bash, but skipping specific functions?

Suppose I have bash_functions.sh: function test(){ } function test2(){ } And in my ~/.bashrc I do: source ~/bash_functions.sh Is it possible to, when sourcing it, avoid sourcing a specific ...
4
votes
1answer
127 views

How can I colorize head, tail and less, same as I've done with cat?

I've got 'color cat' working nicely, thanks to others (see How can i colorize cat output including unknown filetypes in b&w?). In my .bashrc: cdc() { for fn in "$@"; do source-highlight ...
4
votes
2answers
225 views

Function caller positional parameters

I need to read and write the positional parameters $@ of a function's caller. The Bash man page says that: A shell function is an object that is called like a simple command and executes a ...
3
votes
3answers
706 views

Infinitely Nested Directories

Let me start off by saying this is a Mac Terminal I'm using. Not Linux, but I assumed I would get the best answers here as it has to do with Unix and the command line not really anything about Mac ...
3
votes
3answers
76 views

Is there something like closures for zsh?

I just decided to try zsh (through oh-my-zsh), and am now playing with precmd to emulate a two-line prompt that has right prompts in more than just the last line. So I clone the default theme, and ...
3
votes
1answer
336 views

for loop in bash function

I recently wrote the following bash function: makeaudiobook () { count=1 almbumartist=$2 for f in $1; do preprocess $f > $f-preprocessed text2wave $f-preprocessed -o $f.wav ...
3
votes
3answers
2k 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 ...
3
votes
2answers
4k views

Passing a variable to a bash script when sourcing it in another bash script?

Suppose I have in main.sh: NAME="$HOME" if [ -f "$HOME/install.sh" ] then . "$HOME/install.sh" "$NAME" fi and in install.sh: echo $1 This is supposed to echo /home/user/, but it echoes ...
3
votes
2answers
76 views

How to show last command with expanding function in bash

I'm using function like this. $ find-grep () { find . -type f -name "$1" -print0 | xargs -0 grep "$2" ; } After I type: $ find-grep *.c foo I want to get expanded last command string. In this ...
3
votes
1answer
149 views

bash: Accessing function call stack in trap function

Working on a bash function call stack trace... Script traps errors and runs a callStack() function. But on trapping, It always shows a call stack for the callStack() function itself instead of the ...
2
votes
1answer
295 views

Why do Unix-like systems execute a new process when calling a new function?

Why do Unix-like systems execute a new process when calling a function rather than a dynamic library? Creating a new process is costly in terms of performance when compared to calling a dynamic ...
2
votes
2answers
708 views

creating simple command for sudo apt-get install?

I need to run these commands very often: sudo apt-get install <package> sudo apt-get remove <package> Can I make it simple like: install <package> remove <package> I ...
2
votes
4answers
247 views

Scope of variables when calling function from find

In a bash script I define a function that is called from find. The problem is that the scope of variables does not extend to the function. How do I access variables from the function? Here is an ...
2
votes
2answers
109 views

Pass arguments to function exactly as-is

I have the following function: bar() { echo $1:$2; } I am calling this function from another function, foo. foo itself is called as follows: foo "This is" a test I want to get the following ...
2
votes
3answers
42 views

how to prevent alias expansion by `eval` to an arbitrary alias, and keep the endless loop protection on a function?

IMPORTANT: do not use eval! (I learned this later..) In a function, eval expands sleep to its alias, so I prevent the endless loop this way: function FUNCexecEcho() { echo "EXEC: $@"; shopt -u ...
2
votes
3answers
861 views

How to add a function to .bash_profile/.profile/bashrc in shell?

I have a function which converts epoch time to date. Here is the definition date1(){ date -d @$1 } I'd like to be able to write: $ data1 xxxyyy And I want the corresponding date. I understand ...
2
votes
3answers
456 views

Bash source — select the right function when two sourced files have the same function name?

My bash script sources a script file (call it file2.sh) according to an argument. (It is either sourced or not.) The script file2.sh contains a function "foo" (call it a modified or improved version ...
2
votes
3answers
318 views

Prefix every argument with -o in BASH

How do I prefix -p to every argument passed to my function? Modifying the arguments themselves and creating a new array are both fine.
2
votes
3answers
367 views

What are commands to find shell keywords, built in functions and user defined functions?

I was discussing with my friend on how the commands are parsed in the shell, and he told me that bash searches the command in following order List of aliases List of shell keywords List of ...
2
votes
2answers
294 views

Bash: passing braces as arguments to bash function

I love using the following pattern for searching in files: grep --color=auto -iRnHr --include={*.js,*.html,} --exclude-dir={release,dev,} "span" . I'd like, however, to have this one wrapped into a ...
2
votes
2answers
120 views

Is there any way I can fit this into my ~/.bashrc as a function?

I just discovered this useful bit of code on this useful-looking website. #!/bin/sh exec tclsh "$0" ${1+"$@"} proc main {} { set lines [lrange [split [read stdin] \n] 0 end-1] set count ...
2
votes
1answer
83 views

Restoring an option at the end of a function in zsh

I'm writing a zsh shell function (as opposed to a script) where I would really like the extended_glob option to be enabled. But since the function runs in the caller's context, I don't want to clobber ...
2
votes
1answer
20 views

Expand variable in function definition in zsh

I want to generate a set of functions in my shell in a for loop, but I can't see how to access a variable inside the function body of the function I'm creating. In essence, I would like the following ...
2
votes
3answers
354 views

How to reverse-match a string in the Vim programming language?

I want to find the last index of any character in the [abc] set in the abcabc string but the search should start from the end of the string: " Returns the 0th index but I want the 5th. let ...
2
votes
1answer
212 views

awk function with a number parameter for the column you want to print

I want to use my awk shortcut as a function, so that I can pass the column number which then prints me the output. My aliases are: alias A="| awk '{print \$1}' alias G="| grep -i' Instad of typing: ...
2
votes
2answers
126 views

bash: get array name from parameter to function with saving indexes

I have a function to show index of chosen element. I'm trying to pass a parameter to function to use it as an array name. This works: getIndex() { arrname=$1[@] b=("${!arrname}") index=1; while ...