linux 杂

set -e表示一旦脚本中有命令的返回值为非0，则脚本立即退出，后续命令不再执行;

set -o pipefail表示在管道连接的命令序列中，只要有任何一个命令返回非0值，则整个管道返回非0值，即使最后一个命令返回0.

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tput rev  # reverse                    命令行背景反转
tput bold # bold                         字体加粗
echo ‘Please provide a path to a SSH private key to access Manta.‘
tput sgr0 # clear                         回归原状

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if [ -z "$1" ]; then               是空

if [ ! -f "$1" ]; then             文件不存在

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$ command -v foo >/dev/null 2>&1 || { echo >&2 "I require foo but it‘s not installed.  Aborting."; exit 1; }
$ type foo >/dev/null 2>&1 || { echo >&2 "I require foo but it‘s not installed.  Aborting."; exit 1; }
$ hash foo 2>/dev/null || { echo >&2 "I require foo but it‘s not installed.  Aborting."; exit 1; }

判断命令是否存在

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linux 杂

原文：http://www.cnblogs.com/mhc-fly/p/6837388.html