Linux替换文件行首的空白字符

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使用命令sed、cp、tail、cat

1、拷贝一个任意文件（生产环境切勿操作）

cp /etc/profile /tmp

查看文件部分格式

cat /tmp/profile

# /etc/profile# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc# It's NOT a good idea to change this file unless you know what you
# are doing. It's much better to create a custom.sh shell script in
# /etc/profile.d/ to make custom changes to your environment, as this
# will prevent the need for merging in future updates.pathmunge () {
case ":${PATH}:" in
*:"$1":*)
;;
*)
if [ "$2" = "after" ] ; then
PATH=$PATH:$
else
PATH=$:$PATH
fi
esac
}if [ -x /usr/bin/id ]; then
if [ -z "$EUID" ]; then
# ksh workaround
EUID=`/usr/bin/id -u`
UID=`/usr/bin/id -ru`
fi
USER="`/usr/bin/id -un`"
LOGNAME=$USER
MAIL="/var/spool/mail/$USER"
.....
.....
.....

2、使用sed命令替换

sed 's/^ *//' /tmp/profile

root@CentOS7[::]:/tmp# sed 's/^ *//' profile
# /etc/profile# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc# It's NOT a good idea to change this file unless you know what you
# are doing. It's much better to create a custom.sh shell script in
# /etc/profile.d/ to make custom changes to your environment, as this
# will prevent the need for merging in future updates.pathmunge () {
case ":${PATH}:" in
*:"$1":*)
;;
*)
if [ "$2" = "after" ] ; then
PATH=$PATH:$
else
PATH=$:$PATH
fi
esac
}if [ -x /usr/bin/id ]; then
if [ -z "$EUID" ]; then
# ksh workaround
EUID=`/usr/bin/id -u`
UID=`/usr/bin/id -ru`
.....
.....
.....